CA2141034C - Indium antimonide (insb) photodetector device and structure for infrared, visible and ultraviolet radiation - Google Patents
Indium antimonide (insb) photodetector device and structure for infrared, visible and ultraviolet radiationInfo
- Publication number
- CA2141034C CA2141034C CA002141034A CA2141034A CA2141034C CA 2141034 C CA2141034 C CA 2141034C CA 002141034 A CA002141034 A CA 002141034A CA 2141034 A CA2141034 A CA 2141034A CA 2141034 C CA2141034 C CA 2141034C
- Authority
- CA
- Canada
- Prior art keywords
- substrate
- passivation layer
- radiation
- light receiving
- receiving surface
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 230000005855 radiation Effects 0.000 title claims abstract description 31
- WPYVAWXEWQSOGY-UHFFFAOYSA-N indium antimonide Chemical compound [Sb]#[In] WPYVAWXEWQSOGY-UHFFFAOYSA-N 0.000 title claims abstract description 25
- 239000000758 substrate Substances 0.000 claims abstract description 53
- 238000002161 passivation Methods 0.000 claims abstract description 40
- 239000000463 material Substances 0.000 claims abstract description 25
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 11
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 9
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052787 antimony Inorganic materials 0.000 claims abstract description 7
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 7
- 239000010703 silicon Substances 0.000 claims abstract description 7
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 7
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 7
- 229910052738 indium Inorganic materials 0.000 claims abstract description 6
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 claims abstract description 6
- 238000001228 spectrum Methods 0.000 claims description 12
- 230000004044 response Effects 0.000 claims description 10
- 239000004065 semiconductor Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 5
- 229910007277 Si3 N4 Inorganic materials 0.000 claims description 4
- 238000005286 illumination Methods 0.000 claims description 4
- 230000003595 spectral effect Effects 0.000 abstract description 8
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 4
- 238000003491 array Methods 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 229910052814 silicon oxide Inorganic materials 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910000661 Mercury cadmium telluride Inorganic materials 0.000 description 2
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 238000000151 deposition Methods 0.000 description 2
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000010407 anodic oxide Substances 0.000 description 1
- 238000002048 anodisation reaction Methods 0.000 description 1
- 229910001439 antimony ion Inorganic materials 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- MCMSPRNYOJJPIZ-UHFFFAOYSA-N cadmium;mercury;tellurium Chemical compound [Cd]=[Te]=[Hg] MCMSPRNYOJJPIZ-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000002019 doping agent Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010893 electron trap Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 239000002784 hot electron Substances 0.000 description 1
- 229960000443 hydrochloric acid Drugs 0.000 description 1
- 235000011167 hydrochloric acid Nutrition 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 239000004310 lactic acid Substances 0.000 description 1
- 235000014655 lactic acid Nutrition 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052714 tellurium Inorganic materials 0.000 description 1
- PORWMNRCUJJQNO-UHFFFAOYSA-N tellurium atom Chemical compound [Te] PORWMNRCUJJQNO-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
- H01L31/0264—Inorganic materials
- H01L31/0304—Inorganic materials including, apart from doping materials or other impurities, only AIIIBV compounds
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by at least one potential-jump barrier or surface barrier, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier
- H01L31/103—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the PN homojunction type
- H01L31/1035—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier or surface barrier the potential barrier being of the PN homojunction type the devices comprising active layers formed only by AIIIBV compounds
Abstract
The light receiving or back-side surface (22) of an indium antimonide (InSb) photodetector device (10) substrate (12) is cleaned to remove all native oxides of indium and antimony therefrom. A passivation layer (26) is then formed on the surface (22) of a material such as silicon dioxide, silicon suboxide and/or silicon nitride which does not react With InSb to form a structure which would have carrier traps therein and cause flashing. The device (10) is capable of detecting radiation over a continuous spectral range including the infrared, visible and ultraviolet regions.
Description
INDIUM ANTIMONIDE (InSb) PHOTODETECTOR DEVICE AND
STRUCTURE FOR INFRARED, VISIBLE AND ULTRAVIOLET RADIATION
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to an indium antimonide (InSb) photodetector device and photosensitive structure having a passivated light receiving surface which eliminates degradation of photoresponse in the infrared region due to flashing and enables the device to detect radiation in a continuous spectral range including the infrared, visible and ultraviolet regions.
Description of the Related Art Back-side illuminated InSb photodetector devices such as photodiode arrays have been conventionally used for detecting infrared light radiation in a wavelength range of approximately 1- 5.5 micrometers. However, they have been unusable for detecting light in both the infrared and visible regions due to a "flashing' effect which is inherent in conventional back-side passivated/ anti-reflec-i . 2141034 f tion coated InSb devices.
A conventional passivation/anti-reflection coating is formed by anodization of the back-side, or light receiving surface of the photodetector device substrate as described in an article entitled "Formation and Properties of Anodic Oxide Films on Indium Antimonide", by T. Sakurai et al, Japanese Journal of Applied physics, vol: 7, no. 12, Dec. -1968, pp. 1491-1496.
The anodized oxide layer is predominantly microcrys-talline In203 and Sb203 with a high concentration of antimony located interstitially within the oxide film. The antimony ions which are located close to the oxide/InSb interface form carrier traps. The flashing is caused by hot elec-trons generated by photons of visible or ultraviolet light which are captured by these electron traps in the passiva-tion layer. The trapped electrons suppress the infrared sss'~;:
response by recombining with photogenerated minority carriers (holes) before they are collected in the semicon-ductor P-N functions of the device.
The prior art approach to utilization of InSb photode-tectors for detecting infrared radiation is to provide a filter which selectively prevents light of visible and ultraviolet wavelengths from reaching the device. This, of course, renders the device inoperative for detecting visible and ultraviolet light.
The In203 and Sb203 oxides, in addition to any other oxides which may be formed through reaction of indium and/or antimony with oxygen, are referred to as "native oxides". The invention disclosed in the related applica-tion overcomes the flashing problem by eliminating these native oxides and associated carrier traps from the light receiving surface of an InSb photodetector, thereby producing a photodetector device which is capable .pf detecting visible and infrared light in a wavelength range of approximately 0.6 - 5.5 micrometers.
i An antireflection coating is formed over the passivation layer.
Although these layers are successful in performing their intended functions, they prevent the device from detecting radiation of wavelengths shorter than approximately 0.6 micrometers.
SUMMARY OF THE INVENTION
Various aspects of the invention are as follows:
A broadband photodetector device capable of detecting infrared (IR), visible and near-ultraviolet (UV) radiation, comprising:
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-UV
radiation;
a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-UV radiation components; and at least one photosensitive semiconductor junction formed in said substrate;
said detector responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes moving to said photosensitive junction without substantial interference from said near-UV
generated electrons.
A broadband photosensitive structure, comprising:
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-ultraviolet A
3a (UV) radiation; and a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near-W
components;
said photosensitive structure responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes free to move across the substrate without substantial interference from said near-LTV generated electrons.
A broadband photodetector device capable of detecting infrared (IR), visible and near-ultraviolet (LTV) radiation, comprising:
an InSb substrate having a light receiving surface;
a Si3 N4 passivation layer formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-LJV radiation components; and at least one photosensitive semiconductor junction formed in said substrate.
A broadband photosensitive structure, comprising:
a photosensitive InSb substrate having a light receiving surface; and a Si3 N4 passivation layer, approximately 50-150 angstroms thick, formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near UV components.
By way of added explanation, in accordance with an aspect of the present invention, the light receiving or back surface of an InSb photodetector device substrate is cleaned to remove all oxides of indium and antimony a 3b y therefrom. A passivation layer having a thickness of approximately 50 -150 Angstroms is then formed on the back surface of a material which does not react with InSb to form a structure which would have carrier traps therein and cause flashing. The passivation layer preferably includes silicon dioxide, silicon suboxide, silicon nitride or a combination thereof.
The photodetector device of the related application as described above includes, in addition to the structure of the present device, an antireflection coating formed on the passivation layer. The present invention is based on the discovery by the inventors that the device is capable of detecting radiation in a continuous spectral range of approximately 0.3 - 5.5 micrometers.
Since the antireflection coating which blocks radiation of wavelengths shorter than approximately 0.7 micrometers is not present, the present photodetector device is responsive to radiation in the short wavelength portion of the visible spectral region as well as radiation in the near ultraviolet region.
A focal plane array based on the present photodetector device can replace conventional arrays which include separate photodetectors for different spectral regions. This will enable substantial simplification and cost reduction of imaging systems using these arrays.
t These and other features and advantages of the present invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified sectional view of a photodetector device including a photosensitive structure embodying the present invention; and FIG. 2 is a graph illustrating the relative response per photon of the present photodetector device.
DETAILED DESCRIPTION OF THE INVENTION
As illustrated in FIG. 1, an InSb photodetector device embodying the present invention is generally designated as 10, and includes an InSb wafer or substrate 12 having a front surface 14 in which at least one photosensitive semiconductor junction is formed. The substrate 12 is typically lightly doped with an N type dopant such as tellurium. Heavily doped P+ type regions 16 are formed in the surface 14 through ion implantation of beryllium.
Photosensitive semiconductor junctions 18 which constitute photodiodes are formed at the interfaces of the P+ regions 16 and the N-type substrate 12.
Ohmic contracts 20 are formed on the P+ region 16. A complete circuit path for the photodiodes is provided by means which are symbolically indicated by connection of the substrate 12 to ground.
The substrate 12 has a back-side or light receiving back surface 22 which is designated to receive incident light for detection by the device 10 as indicated by arrows 24. The substrate 12 is thin enough (approximately 8 -12 micrometers thick) for the photogenerated carriers to diffuse therethrough from beneath the surface 22 to the junctions 18 and cause carrier collection at the junctions 4~~
~1 ~14,3~
18.
f During the fabrication process of the device 10, the surface 22 is thoroughly cleaned to remove a11 native oxides of indium and antimony therefrom. A passivation 5 layer 26 is formed on the back surface 22 of a material which will not react with indium antimonide (InSb) to form either native oxides or any other substance or structure which would have carrier traps therein and cause flashing.
The passivation layer 26 is preferably formed of an l0 silicon oxide and/or nitride material, although the scope of the invention is not so limited. The passivation layer 26 may be formed of any material which will not produce carrier traps when formed on the surface 22, will passivate the surface 22 by preventing reaction thereof with the ambient atmosphere, and is substantially transparent to infrared, visible and ultraviolet light in a continuous spectral range.
For the purposes of the present disclosure, the term "substantially transparent" means that the passivation ' 20 layer 26 is sufficiently transparent to light within the selected wavelength range to enable the device l0 to provide useful operation. Although not illustrated, the scope of the invention further includes forming an anti.-reflection coating over the passivation layer 26 of a ' 25 material which is also substantially transparent to light in the selected wavelength range.
The passivation layer 26 may be formed using a conventional plasma deposition technique. The preferred materials for the layer 26 are silicon dioxide .~Si02), 30 silicon suboxide (SiOy) where 0 <_ y _< 2, silicon nitride i (Si3N4) or a combination or mixture thereof. The generic composition of these materials is SiXOyNz, where x = 1 or 3, 0 < y <_ 2 and z = 0 , 1 or 4 .
FIG. 2 illustrates the performance of the present 35 photodetector device 10. The quantum efficiency of the 2141~3~
f device 10 in terms of the relative photoresponse per photon is~plotted as a function of wavelength. A reference level as indicated by a broken line 30 corresponds to a quantum efficiency of 0.63 at a wavelength of 4.0 micrometers. It will be seen that the range of useful photoresponse extends continuously from approximately 0.3 - 5.5 micrometers, including the near ultraviolet (UV), visible, short wave infrared (SWIR) and medium wave infrared (MWIR) spectral regions.
The data for wavelengths shorter than 1.0 micrometer was taken with a Cary 14 spectrometer using a quartz-halogen light source. The data for wavelengths longer than 1.0 micrometer was taken with a Perkin-Elmer 13U prism monochromator. A discontinuity of approximately 10~ exists at the 1.0 micrometer interface. However, the data is sufficiently accurate to demonstrate the useful photore sponse of the present device 10 in the infrared, visible ~iilat:~::
and ultraviolet spectral regions.
~20 EXAMPLE
Experimental photodetector devices which produced the results illustrated in FIG. 2 were fabricated using the following procedure.
' 25 (1) The P+ regions 16, contacts 20, and other associated elements were formed in the front side 14 of an InSb substrate or wafer 12 which was initially 750 microme-ters thick to form operative photodiode junctions 18.
(2) The back side 22 was abraded until the thickness 30 of the substrate 12 was reduced to approximately 15 micrometers.
(3) The front side 14 of the substrate 12 was mounted on a sapphire slide, and areas of the.back side 22 exce.~t on which the passivation layer 26 was to be formed were 35 protected with a thick coating of photoresist.
E
STRUCTURE FOR INFRARED, VISIBLE AND ULTRAVIOLET RADIATION
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to an indium antimonide (InSb) photodetector device and photosensitive structure having a passivated light receiving surface which eliminates degradation of photoresponse in the infrared region due to flashing and enables the device to detect radiation in a continuous spectral range including the infrared, visible and ultraviolet regions.
Description of the Related Art Back-side illuminated InSb photodetector devices such as photodiode arrays have been conventionally used for detecting infrared light radiation in a wavelength range of approximately 1- 5.5 micrometers. However, they have been unusable for detecting light in both the infrared and visible regions due to a "flashing' effect which is inherent in conventional back-side passivated/ anti-reflec-i . 2141034 f tion coated InSb devices.
A conventional passivation/anti-reflection coating is formed by anodization of the back-side, or light receiving surface of the photodetector device substrate as described in an article entitled "Formation and Properties of Anodic Oxide Films on Indium Antimonide", by T. Sakurai et al, Japanese Journal of Applied physics, vol: 7, no. 12, Dec. -1968, pp. 1491-1496.
The anodized oxide layer is predominantly microcrys-talline In203 and Sb203 with a high concentration of antimony located interstitially within the oxide film. The antimony ions which are located close to the oxide/InSb interface form carrier traps. The flashing is caused by hot elec-trons generated by photons of visible or ultraviolet light which are captured by these electron traps in the passiva-tion layer. The trapped electrons suppress the infrared sss'~;:
response by recombining with photogenerated minority carriers (holes) before they are collected in the semicon-ductor P-N functions of the device.
The prior art approach to utilization of InSb photode-tectors for detecting infrared radiation is to provide a filter which selectively prevents light of visible and ultraviolet wavelengths from reaching the device. This, of course, renders the device inoperative for detecting visible and ultraviolet light.
The In203 and Sb203 oxides, in addition to any other oxides which may be formed through reaction of indium and/or antimony with oxygen, are referred to as "native oxides". The invention disclosed in the related applica-tion overcomes the flashing problem by eliminating these native oxides and associated carrier traps from the light receiving surface of an InSb photodetector, thereby producing a photodetector device which is capable .pf detecting visible and infrared light in a wavelength range of approximately 0.6 - 5.5 micrometers.
i An antireflection coating is formed over the passivation layer.
Although these layers are successful in performing their intended functions, they prevent the device from detecting radiation of wavelengths shorter than approximately 0.6 micrometers.
SUMMARY OF THE INVENTION
Various aspects of the invention are as follows:
A broadband photodetector device capable of detecting infrared (IR), visible and near-ultraviolet (UV) radiation, comprising:
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-UV
radiation;
a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-UV radiation components; and at least one photosensitive semiconductor junction formed in said substrate;
said detector responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes moving to said photosensitive junction without substantial interference from said near-UV
generated electrons.
A broadband photosensitive structure, comprising:
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-ultraviolet A
3a (UV) radiation; and a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near-W
components;
said photosensitive structure responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes free to move across the substrate without substantial interference from said near-LTV generated electrons.
A broadband photodetector device capable of detecting infrared (IR), visible and near-ultraviolet (LTV) radiation, comprising:
an InSb substrate having a light receiving surface;
a Si3 N4 passivation layer formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-LJV radiation components; and at least one photosensitive semiconductor junction formed in said substrate.
A broadband photosensitive structure, comprising:
a photosensitive InSb substrate having a light receiving surface; and a Si3 N4 passivation layer, approximately 50-150 angstroms thick, formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near UV components.
By way of added explanation, in accordance with an aspect of the present invention, the light receiving or back surface of an InSb photodetector device substrate is cleaned to remove all oxides of indium and antimony a 3b y therefrom. A passivation layer having a thickness of approximately 50 -150 Angstroms is then formed on the back surface of a material which does not react with InSb to form a structure which would have carrier traps therein and cause flashing. The passivation layer preferably includes silicon dioxide, silicon suboxide, silicon nitride or a combination thereof.
The photodetector device of the related application as described above includes, in addition to the structure of the present device, an antireflection coating formed on the passivation layer. The present invention is based on the discovery by the inventors that the device is capable of detecting radiation in a continuous spectral range of approximately 0.3 - 5.5 micrometers.
Since the antireflection coating which blocks radiation of wavelengths shorter than approximately 0.7 micrometers is not present, the present photodetector device is responsive to radiation in the short wavelength portion of the visible spectral region as well as radiation in the near ultraviolet region.
A focal plane array based on the present photodetector device can replace conventional arrays which include separate photodetectors for different spectral regions. This will enable substantial simplification and cost reduction of imaging systems using these arrays.
t These and other features and advantages of the present invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified sectional view of a photodetector device including a photosensitive structure embodying the present invention; and FIG. 2 is a graph illustrating the relative response per photon of the present photodetector device.
DETAILED DESCRIPTION OF THE INVENTION
As illustrated in FIG. 1, an InSb photodetector device embodying the present invention is generally designated as 10, and includes an InSb wafer or substrate 12 having a front surface 14 in which at least one photosensitive semiconductor junction is formed. The substrate 12 is typically lightly doped with an N type dopant such as tellurium. Heavily doped P+ type regions 16 are formed in the surface 14 through ion implantation of beryllium.
Photosensitive semiconductor junctions 18 which constitute photodiodes are formed at the interfaces of the P+ regions 16 and the N-type substrate 12.
Ohmic contracts 20 are formed on the P+ region 16. A complete circuit path for the photodiodes is provided by means which are symbolically indicated by connection of the substrate 12 to ground.
The substrate 12 has a back-side or light receiving back surface 22 which is designated to receive incident light for detection by the device 10 as indicated by arrows 24. The substrate 12 is thin enough (approximately 8 -12 micrometers thick) for the photogenerated carriers to diffuse therethrough from beneath the surface 22 to the junctions 18 and cause carrier collection at the junctions 4~~
~1 ~14,3~
18.
f During the fabrication process of the device 10, the surface 22 is thoroughly cleaned to remove a11 native oxides of indium and antimony therefrom. A passivation 5 layer 26 is formed on the back surface 22 of a material which will not react with indium antimonide (InSb) to form either native oxides or any other substance or structure which would have carrier traps therein and cause flashing.
The passivation layer 26 is preferably formed of an l0 silicon oxide and/or nitride material, although the scope of the invention is not so limited. The passivation layer 26 may be formed of any material which will not produce carrier traps when formed on the surface 22, will passivate the surface 22 by preventing reaction thereof with the ambient atmosphere, and is substantially transparent to infrared, visible and ultraviolet light in a continuous spectral range.
For the purposes of the present disclosure, the term "substantially transparent" means that the passivation ' 20 layer 26 is sufficiently transparent to light within the selected wavelength range to enable the device l0 to provide useful operation. Although not illustrated, the scope of the invention further includes forming an anti.-reflection coating over the passivation layer 26 of a ' 25 material which is also substantially transparent to light in the selected wavelength range.
The passivation layer 26 may be formed using a conventional plasma deposition technique. The preferred materials for the layer 26 are silicon dioxide .~Si02), 30 silicon suboxide (SiOy) where 0 <_ y _< 2, silicon nitride i (Si3N4) or a combination or mixture thereof. The generic composition of these materials is SiXOyNz, where x = 1 or 3, 0 < y <_ 2 and z = 0 , 1 or 4 .
FIG. 2 illustrates the performance of the present 35 photodetector device 10. The quantum efficiency of the 2141~3~
f device 10 in terms of the relative photoresponse per photon is~plotted as a function of wavelength. A reference level as indicated by a broken line 30 corresponds to a quantum efficiency of 0.63 at a wavelength of 4.0 micrometers. It will be seen that the range of useful photoresponse extends continuously from approximately 0.3 - 5.5 micrometers, including the near ultraviolet (UV), visible, short wave infrared (SWIR) and medium wave infrared (MWIR) spectral regions.
The data for wavelengths shorter than 1.0 micrometer was taken with a Cary 14 spectrometer using a quartz-halogen light source. The data for wavelengths longer than 1.0 micrometer was taken with a Perkin-Elmer 13U prism monochromator. A discontinuity of approximately 10~ exists at the 1.0 micrometer interface. However, the data is sufficiently accurate to demonstrate the useful photore sponse of the present device 10 in the infrared, visible ~iilat:~::
and ultraviolet spectral regions.
~20 EXAMPLE
Experimental photodetector devices which produced the results illustrated in FIG. 2 were fabricated using the following procedure.
' 25 (1) The P+ regions 16, contacts 20, and other associated elements were formed in the front side 14 of an InSb substrate or wafer 12 which was initially 750 microme-ters thick to form operative photodiode junctions 18.
(2) The back side 22 was abraded until the thickness 30 of the substrate 12 was reduced to approximately 15 micrometers.
(3) The front side 14 of the substrate 12 was mounted on a sapphire slide, and areas of the.back side 22 exce.~t on which the passivation layer 26 was to be formed were 35 protected with a thick coating of photoresist.
E
(4) The surface 22 was plasma ashed using oxygen plasma for 10 minutes at a pressure of 0.5 Torr and power of 150 W.
(5) The surface 22 was chemically etched using a two step process.
(a) 30 seconds in a 50/50 solution of hydrochlo-ric acid/de-ionized water. -(b) 3 minutes in a 70/10 solution of lactic acid/nitric acid.
Steps (4) and (5) in combination cleaned the back surface 22 by removing the native oxides, crystal damage caused by the thinning process in step (2), and some of the InSb material, such that the final thickness of the substrate 12 was between approximately 8 to 12 micrometers.
(a) 30 seconds in a 50/50 solution of hydrochlo-ric acid/de-ionized water. -(b) 3 minutes in a 70/10 solution of lactic acid/nitric acid.
Steps (4) and (5) in combination cleaned the back surface 22 by removing the native oxides, crystal damage caused by the thinning process in step (2), and some of the InSb material, such that the final thickness of the substrate 12 was between approximately 8 to 12 micrometers.
(6) The substrate 12 was rinsed in a de-ionized water bath, and dried by NZ gas flow. The following step of applying the passivation layer 26 was perfonued within a sufficiently short length of time that no appreciable native oxides were able to form on the surface 22 through f20 exposure to the ambient atmosphere.
(7) The passivation layer 26 was formed on the surface 22 of the substrate 12 using conventional plasma deposition., The passivation layer 26 was a mixture of SiOi and Si3N4 and was formed from a plasma including N2, 02, and ' 25 silane (SiH4) .
While an illustrative embodiment of the invention has been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art, without departing from the spirit and scope of the invention:
30 For example, although the embodiment of the invention as described and illustrated includes an indium antimonide substrate and a silicon oxide or nitride passivation layer, the scope of the invention encompasses the use of other substrate materials such as mercury cadmium telluride 35 (HgCdTe), as well as other materials for the passivation z1~1~~4 f layer.
Accordingly, it is intended that the present invention not be limited solely to the specifically described illustrative embodiment. Various modifications are contemplated and can be made without departing from the spirit and scope of the invention as defined by the appended claims.
t
While an illustrative embodiment of the invention has been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art, without departing from the spirit and scope of the invention:
30 For example, although the embodiment of the invention as described and illustrated includes an indium antimonide substrate and a silicon oxide or nitride passivation layer, the scope of the invention encompasses the use of other substrate materials such as mercury cadmium telluride 35 (HgCdTe), as well as other materials for the passivation z1~1~~4 f layer.
Accordingly, it is intended that the present invention not be limited solely to the specifically described illustrative embodiment. Various modifications are contemplated and can be made without departing from the spirit and scope of the invention as defined by the appended claims.
t
Claims (15)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A broadband photodetector device capable of detecting infrared (IR), visible and near-ultraviolet (UV) radiation, comprising:
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-UV
radiation;
a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-UV radiation components; and at least one photosensitive semiconductor junction formed in said substrate;
said detector responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes moving to said photosensitive junction without substantial interference from said near-UV generated electrons.
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-UV
radiation;
a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-UV radiation components; and at least one photosensitive semiconductor junction formed in said substrate;
said detector responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes moving to said photosensitive junction without substantial interference from said near-UV generated electrons.
2. A device as in claim 1, in which:
the substrate comprises indium antimonide; and said native oxides of which said surface is substantially free comprise oxides of indium and antimony.
the substrate comprises indium antimonide; and said native oxides of which said surface is substantially free comprise oxides of indium and antimony.
3. A device as in claim 2, in which the passivation layer is approximately 50-150 angstroms thick.
4. A device as in claim 2, in which the passivation layer comprises a material selected from the group consisting of silicon dioxide, silicon suboxide and silicon nitride.
5. A device as in claim 2, in which the passivation layer comprises silicon nitride and a material selected from the group consisting of silicon dioxide and silicon suboxide.
6. A device as in claim 2, in which the passivation layer comprises a material having the composition Si x O y N z, where x=1 or 3, 0~y~2 and z=0, 1 or 4.
7. A broadband photosensitive structure, comprising:
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-ultraviolet (UV) radiation; and a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near-UV components;
said photosensitive structure responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes free to move across the substrate without substantial interference from said near-UV generated electrons.
a photosensitive substrate formed from a material that has a light receiving surface which is substantially free of native oxides of any components of the substrate material, and accordingly has substantially no carrier traps for electrons excited in the substrate by incident near-ultraviolet (UV) radiation; and a passivation layer formed on said substantially native oxide-free light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near-UV components;
said photosensitive structure responding to illumination of said light receiving surface with light over said broadband spectrum by generating electrons in the substrate in response to said near-UV radiation, and generating electron-hole pairs in response to the IR component, with said holes free to move across the substrate without substantial interference from said near-UV generated electrons.
8. A structure as in claim 7, in which:
the substrate comprises indium antimonide; and said native oxides of which said surface is substantially free comprise oxides of indium and antimony.
the substrate comprises indium antimonide; and said native oxides of which said surface is substantially free comprise oxides of indium and antimony.
9. A structure as in claim 8, in which the passivation layer is approximately 50-150 angstroms thick.
10. A structure as in claim 8, in which the passivation layer comprises a material selected from the group consisting of silicon dioxide, silicon suboxide and silicon nitride.
11. A structure as in claim 8, in which the passivation layer comprises silicon nitride and a material selected from the group consisting of silicon dioxide and silicon suboxide.
12. A structure as in claim 8, in which the passivation layer comprises a material having the composition Si x O y N z, where x=1 or 3, 0~y~2 and z=0, 1 or 4.
13. A broadband photodetector device capable of detecting infrared (IR), visible and near-ultraviolet (UV) radiation, comprising:
an InSb substrate having a light receiving surface;
a Si3 N4 passivation layer formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-UV
radiation components; and at least one photosensitive semiconductor junction formed in said substrate.
an InSb substrate having a light receiving surface;
a Si3 N4 passivation layer formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein, said passivation layer being substantially transparent to a broadband spectrum that includes IR, visible and near-UV
radiation components; and at least one photosensitive semiconductor junction formed in said substrate.
14. A device as in claim 13, in which the passivation layer is approximately 50-150 angstroms thick.
15. A broadband photosensitive structure, comprising:
a photosensitive InSb substrate having a light receiving surface; and a Si3 N4 passivation layer, approximately 50-150 angstroms thick, formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near UV components.
a photosensitive InSb substrate having a light receiving surface; and a Si3 N4 passivation layer, approximately 50-150 angstroms thick, formed on said light receiving surface which does not react with the substrate to form a structure which would have carrier traps therein and is substantially transparent to a broadband spectrum of radiation having infrared, visible and near UV components.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US6889793A | 1993-05-28 | 1993-05-28 | |
| US068,897 | 1993-05-28 | ||
| PCT/US1994/006038 WO1994028587A1 (en) | 1993-05-28 | 1994-05-27 | INDIUM ANTIMONIDE (InSb) PHOTODETECTOR DEVICE AND STRUCTURE FOR INFRARED, VISIBLE AND ULTRAVIOLET RADIATION |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2141034A1 CA2141034A1 (en) | 1994-12-08 |
| CA2141034C true CA2141034C (en) | 1999-07-27 |
Family
ID=22085408
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002141034A Expired - Fee Related CA2141034C (en) | 1993-05-28 | 1994-05-27 | Indium antimonide (insb) photodetector device and structure for infrared, visible and ultraviolet radiation |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0653106A1 (en) |
| JP (1) | JP2998994B2 (en) |
| CA (1) | CA2141034C (en) |
| WO (1) | WO1994028587A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2461914C1 (en) * | 2011-06-14 | 2012-09-20 | Открытое акционерное общество "Московский завод "САПФИР" | Planar photodiode on indium antimonide |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4286277A (en) * | 1977-11-22 | 1981-08-25 | The United States Of America As Represented By The Secretary Of The Army | Planar indium antimonide diode array and method of manufacture |
| JPS6237927A (en) * | 1985-08-13 | 1987-02-18 | Tech Res & Dev Inst Of Japan Def Agency | Preparation for insb semiconductor device |
| DE3617229C2 (en) * | 1986-05-22 | 1997-04-30 | Aeg Infrarot Module Gmbh | Radiation detector |
| CA2070708C (en) * | 1991-08-08 | 1997-04-29 | Ichiro Kasai | Visible and infrared indium antimonide (insb) photodetector with non-flashing light receiving surface |
-
1994
- 1994-05-27 CA CA002141034A patent/CA2141034C/en not_active Expired - Fee Related
- 1994-05-27 EP EP94919282A patent/EP0653106A1/en not_active Withdrawn
- 1994-05-27 WO PCT/US1994/006038 patent/WO1994028587A1/en not_active Application Discontinuation
- 1994-05-27 JP JP7500998A patent/JP2998994B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08500940A (en) | 1996-01-30 |
| CA2141034A1 (en) | 1994-12-08 |
| WO1994028587A1 (en) | 1994-12-08 |
| JP2998994B2 (en) | 2000-01-17 |
| EP0653106A1 (en) | 1995-05-17 |
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