CN102738333A

CN102738333A - Green light emitting diode and manufacturing method thereof

Info

Publication number: CN102738333A
Application number: CN2012101096159A
Authority: CN
Inventors: 颜建锋; 林桂荣; 庄文荣
Original assignee: JIANGSU HELIOS TECHNOLOGY CO LTD
Current assignee: JIANGSU HELIOS TECHNOLOGY CO LTD
Priority date: 2012-04-16
Filing date: 2012-04-16
Publication date: 2012-10-17
Anticipated expiration: 2032-04-16
Also published as: CN102738333B

Abstract

The invention discloses a green light emitting diode and a manufacturing method thereof. The green light emitting diode is characterized in that a low-temperature protective layer is introduced during epitaxial growth of an InGaN (Indium Gallium Nitride)/GaN (Gallium Nitride) quantum well; the quantum well structure changes from InGaN/GaN to an InGan/Gan low-temperature protective layer 1/GaN structure; thereby protecting In in the InGaN/GaN, and avoiding damage to the In in high-temperature growth, and thus effectively avoiding phase separation of an In component in the InGaN, and improving the internal quantum efficiency; and in addition, two different stress relieving layers are located between an n-type layer and a green light emitting layer, and thus the stress of the green light emitting diode is decreased.

Description

A kind of green light LED and preparation method thereof

Technical field

The present invention relates to a kind of green light LED and preparation method thereof, belong to light-emitting diode and preparation method thereof field.

Background technology

Light-emitting diode has that volume is little, efficient is high and advantage such as the life-span is long; Show in traffic, field such as indoor and outdoor panchromatic demonstration has a wide range of applications; GaN base III-V group-III nitride with broad stopband direct gap semiconductor material is owing to bandgap range under its room temperature contains 0.7eV to 6.2eV; Corresponding wavelength has covered whole visible region and infrared region, ultra-violet (UV) band; GaN base III-V group nitride material has a wide range of applications at optoelectronic areas such as semiconductor solid lighting and panchromatic demonstrations, has become the research focus of optoelectronic areas at present.

GaN based light-emitting diode major product has white light-emitting diodes, blue light diode and green diode.The luminous efficiency of GaN base white light-emitting diodes and blue light diode was greatly improved in recent years, however the luminous efficiency of green light LED compare with the basic white light of GaN and blue light diode will be low many.This mainly is the multi-quantum pit structure as In (Al) GaN/ (Al) GaN because of the present GaN diode that we use, and relative white light and the lower In component of blue light diode, green diode then needs high relatively In component could obtain corresponding wavelength.The In of high In component (Al) GaN material causes being separated of In easily, makes that the SQW number is many more in the crystal mass variation of In (Al) GaN/ (Al) GaN, is easy to generate a large amount of defectives more, thereby makes the luminous efficiency of green diode reduce, electrically variation; Simultaneously; Because the lattice constant (0.3545 nm) of InN is big more a lot of than the lattice constant (0.3189) of GaN; The increase of In component will inevitably make its mismatch become big in the multi-quantum pit structure of In (Al) GaN/ (Al) GaN; It is big that thereby the stress of the SQW that is becomes, and the increase of stress has further reduced the luminous efficiency of green light LED again.So how to reduce In separates and reduce stress, is our present problem demanding prompt solution.

Summary of the invention

The object of the present invention is to provide a kind of new green light LED and preparation method thereof; Through introducing one deck low-temperature protection layer at the green luminescence layer of diode; And stress release layer, the In among the protection InGaN avoids being separated of In component; Stress in the control green glow SQW, thereby the luminous efficiency of raising green diode.

The concrete MOCVD technology that adopts; Utilize high-purity N H3 to do the N source; High-purity H2 or high-purity N 2 are done carrier gas, and trimethyl gallium TMGa or triethyl-gallium TEGa, trimethyl indium TMIn and trimethyl aluminium TMAl do Ga source, In source and aluminium source respectively, utilize silane SiH4, two luxuriant magnesium CP2Mg to do n type Si doped source and p type Mg doped source respectively; It is characterized in that this method may further comprise the steps:

Step 1 is heated to substrate more than 1100 ℃ in the MOCVD reative cell, and as carrier gas, the high-temperature process time is 200-2000 second with the mist of H2 or N2 or H2 and N2;

Step 2 is reduced to 500-600 ℃ to underlayer temperature, utilizes H2 as carrier gas, feeds the thick GaN nucleating layer of trimethyl gallium TMGa or triethyl-gallium TEGa and NH3 growth 20-40nm; Be elevated to underlayer temperature more than 1000 ℃ then, utilize H2, the involuntary Doped GaN layer of epitaxial growth 1-2 micron thick as carrier gas; Be elevated to underlayer temperature more than 1060 ℃ then, utilize H2 as carrier gas, the GaN layer that the n type Si of epitaxial growth 2-4 micron thick mixes, doping content is controlled at-5.0E+18----1.5E+19 cm ^-3

Step 3 drops to 780 ℃ ± 25 ℃ with underlayer temperature, utilizes N2 to do carrier gas; Triethyl-gallium TEGa does the Ga source; Epitaxial growth InGaN/GaN quantum well structure is used for proof stress on the GaN layer that n type Si mixes, and this layer can be a single heterojunction, also can be the volume minor structure; More can be superlattice structure, the wavelength of luminescence generated by light PL spectrum of finally controlling this layer be between 445nm-475nm.

Step 4 is brought up to 810 ℃ ± 25 ℃ with underlayer temperature, utilizes N2 to do carrier gas, and triethyl-gallium TEGa does the Ga source, the above thickness of continued growth 500 dusts, and doping content is at-8.0E+16---the GaN layer that the n type Si of 2.5E+18 cm-3 mixes;

Step 5 is reduced to 730 ℃ ± 10 ℃ with underlayer temperature, utilizes N2 to do carrier gas; Triethyl-gallium TEGa does the Ga source; Continue the green luminescence layer of epitaxial growth InGaN, GaN low-temperature protection layer, GaN, wherein the THICKNESS CONTROL of InGaN layer is at 25 dusts, and the growth temperature of GaN low-temperature protection layer is identical with the InGaN layer still grows under 730 ℃ ± 10 ℃ temperature; THICKNESS CONTROL is at 10-100 dusts; Reduce losing of In among the InGaN, the growth temperature of GaN is controlled at 880 ℃ ± 10 ℃, and the wavelength control of the luminescence generated by light PL spectrum of green luminescence layer is at 520nm;

Step 6 is elevated to 900-950 ℃ with underlayer temperature, and the Mg doping content that growth 30nm is thick on the green luminescence layer quantum well layer of InGaN, GaN low-temperature protection layer, GaN is at 1.5E+21cm ^-3The thick Mg doping content of p type AlGaN electronic barrier layer and 150nm at 1.0E+21cm ^-3P type GaN layer.

The high-temperature process time is preferably 880 seconds in the step 1.

The wavelength of luminescence generated by light PL spectrum preferably is controlled at 465nm in the step 3, can Optimal Control stress.

The whole growth thickness of step 3 and step 4 preferably is controlled at more than 1500 dusts.

The whole growth thickness of step 3 and step 4 preferably is controlled at the 2200-2500 dust.

GaN low-temperature protection layer thickness preferably is controlled at 30 dusts in the step 5.

Low-temperature protection layer structure described in the present invention is not limited only to be used for green diode.

Description of drawings

Accompanying drawing among the present invention only is used to make things convenient for those skilled in the art that the present invention is further understood, must not be as the qualification of claim protection range.

Fig. 1, green light LED structure chart are from top to bottom: substrate (1), intrinsic layer (2), n-type layer (3), stress release layer 1 (4), defective filter course and stress release layer 2 (5), green luminescence layer (6), electronic barrier layer (7), p-type layer (8).Intrinsic layer (2) is made up of GaN and non-Doped GaN; N-type layer (3) is n-Gan:Si; Stress release layer 1 (4) is that InGaN trap layer and GaN build layer and form, and defective filter course (5) and stress release layer 2 (6) are made up of n-Gan:Si, and green luminescence layer (7) layer is made up of green glow InGaN SQW, green glow GaN low-temperature protection layer, green glow GaN base; Electronic barrier layer (8) is AlGaN, and p-type layer (9) is p-GaN.

The luminescence generated by light figure (PL) of Fig. 2, green diode

Embodiment

Embodiment among the present invention only is used for the present invention is further explained, must not be as the qualification of claim protection range.

Embodiment 1

As shown in Figure 1, growth high brightness green light LED is heated to Sapphire Substrate 1 more than 1000 ℃, in N in the MOVCD reative cell ₂As carrier gas, handled 880 seconds, then underlayer temperature is reduced to 500-600 ℃, N ₂Switch to H ₂As carrier gas, feed TMGa and NH3 growing GaN nucleating layer, thickness is about 35nm; Be increased to underlayer temperature more than 1000 ℃, utilize H2, about the involuntary doped layer GaN1.5 of epitaxial growth micron as carrier gas; More than the rising underlayer temperature to 1060 ℃, still use H2 as carrier gas, the GaN layer that the n type Si of 3 micron thick of growing mixes, doping content is-2.5E+17; Underlayer temperature is reduced to about 780 ℃; N2 is as carrier gas; Utilize TEGa as the Ga source; Growth thickness is that the right InGaN/GaN quantum well structure of 2000 Izods is used for proof stress on the GaN layer that n type Si mixes, and the wavelength of luminescence generated by light PL spectrum of finally controlling this layer is about 450nm, to reduce the stress in the SQW.Underlayer temperature is brought up to about 810 ℃, utilized N2 to do carrier gas, triethyl-gallium TEGa does the Ga source, the above thickness of continued growth 500 dusts, and doping content is at-2E+17 cm ^-3About the GaN layer that mixes of n type Si; Underlayer temperature is reduced to about 730 ℃; Utilize N2 to do carrier gas, triethyl-gallium TEGa does the Ga source, continues the green luminescence layer of epitaxial growth InGaN, GaN low-temperature protection layer, GaN; Wherein the THICKNESS CONTROL of InGaN layer is at 25 dusts; The growth temperature of GaN low-temperature protection layer is identical with the InGaN layer still grows under 730 ℃ of left and right sides temperature, and THICKNESS CONTROL is right at 50 Izods, and In's loses among the reduction InGaN; The growth temperature of GaN is controlled at about 880 ℃, and the wavelength control of the luminescence generated by light PL spectrum of green luminescence layer is at 520nm; Underlayer temperature is elevated to 900-950 ℃, and the Mg doping content that growth 30nm is thick on the green luminescence layer quantum well layer of InGaN, GaN low-temperature protection layer, GaN is at 1.5E+21cm ^-3The thick Mg doping content of p type AlGaN electronic barrier layer and 150nm at 1.0E+21cm ^-3P type GaN layer.

Growth thickness is the right InGaN/GaN quantum well layer of 2000 Izods as stress release layer 1 and on it more than growth thickness 500 dusts on the GaN layer that the present invention mainly mixes through n type Si in epitaxial growth, and doping content is at-2E+17 cm ^-3About the GaN layer that mixes of n type Si as stress release layer 2 and defective filter course, be used for proof stress and discharge, in the InGaN/GaN of green luminescence layer SQW, insert GaN low-temperature protection layer, be used for reducing separating out of SQW In component.

Checking through the extension chip results; Adopt the green light LED of this structure, the chip that is of a size of 300um * 300um, wavelength and is 522nm under the 20mA operating current, 1) only see the green light peak of 520nm in the electroluminescence spectrum; 2) luminous intensity has been brought up to 400mcd by 250mcd; 3) antistatic ESD brings up to more than the HM8000 from HM1000,4) the forward operating voltage has reduced 0.15V (being reduced to 3.05V by 3.2V), simultaneously the cut-in voltage of chip by.19V has brought up to more than the 2.3V.The luminescence generated by light figure of green diode sees Fig. 2.

Claims

1. a green light LED is characterized in that the green light LED structure is substrate (1), intrinsic layer (2), n-type layer (3), stress release layer 1 (4), defective filter course and stress release layer 2 (5), green luminescence layer (6), electronic barrier layer (7), p-type layer (8) from top to bottom.

2. the described green light LED of claim 1 is characterized in that being made up of two-layer different stress release layer between its n-type layer (3) and the green luminescence layer (6).

3. the described green light LED of claim 2 is characterized in that stress release layer 1 builds layer by InGaN trap layer and GaN and form.

4. the described green light LED of claim 3 is characterized in that InGaN/GaN quantum trap growth temperature is 780 ℃ ± 25 ℃.

5. the described green light LED of claim 2 is characterized in that defective filter course, stress release layer 2 be made up of the GaN layer that n type Si mixes.

6. the described green light LED of claim 5 is characterized in that the GaN layer growth temperature that n type Si mixes is 810 ℃ ± 25 ℃, and doping content is-5.0E+18----1.5E+19 cm ^-3

7. the described green light LED of claim 1 is characterized in that green luminescence layer quantum well structure is InGaN, low-temperature protection layer, GaN from top to bottom.

8. the described green light LED of claim 7 is characterized in that the low-temperature protection layer is GaN.

9. the described green light LED of claim 8, the growth temperature that it is characterized in that low-temperature protection layer GaN is 730 ℃ ± 10 ℃.

10. the preparation method of the described green light LED of claim 1-9; Adopt the MOCVD technology, utilize high-purity N H3 to do the N source, high-purity H2 or high-purity N 2 are done carrier gas; Trimethyl gallium TMGa or triethyl-gallium TEGa, trimethyl indium TMIn and trimethyl aluminium TMAl do Ga source, In source and aluminium source respectively; Utilize silane SiH4, two luxuriant magnesium CP2Mg to do n type Si doped source and p type Mg doped source respectively, it is characterized in that this method may further comprise the steps:

Step 3 drops to 780 ℃ ± 25 ℃ with underlayer temperature, utilizes N2 to do carrier gas; Triethyl-gallium TEGa does the Ga source; Epitaxial growth InGaN/GaN quantum well structure on the GaN layer that n type Si mixes, this layer can be a single heterojunction, also can be the volume minor structure; More can be superlattice structure, the wavelength of luminescence generated by light PL spectrum of finally controlling this layer be between 445nm-475nm;

Step 4 is brought up to 810 ℃ ± 25 ℃ with underlayer temperature, utilizes N2 to do carrier gas, and triethyl-gallium TEGa does the Ga source, the above thickness of continued growth 500 dusts, and doping content is at-8.0E+16---2.5E+18 cm ^-3The GaN layer that mixes of n type Si;

Step 5 is reduced to 730 ℃ ± 10 ℃ with underlayer temperature, utilizes N ₂Do carrier gas; Triethyl-gallium TEGa does the Ga source, the green luminescence layer of continuous mutually epitaxial growth InGaN, GaN low-temperature protection layer, GaN, and wherein the THICKNESS CONTROL of InGaN layer is at 25 dusts; The growth temperature of GaN low-temperature protection layer is identical with the InGaN layer; THICKNESS CONTROL is at 10-100 dusts, and the growth temperature of GaN is controlled at 880 ℃ ± 10 ℃, and the wavelength control of the luminescence generated by light PL spectrum of green luminescence layer is at 520nm;

11. the described method of claim 10 is characterized in that the high-temperature process time is 880 seconds in the step 1.

12. the described method of claim 10, the wavelength control that it is characterized in that luminescence generated by light PL spectrum in the step 3 is at 465nm.

13. the described method of claim 10 is characterized in that the whole growth thickness of step 3 and step 4 is controlled at more than 1500 dusts.

14. the described method of claim 13 is characterized in that the whole growth thickness of step 3 and step 4 is controlled at the 2200-2500 dust.

15. the described method of claim 10 is characterized in that GaN low-temperature protection layer thickness is controlled at 30 dusts in the step 5.