CN103441197B - A kind of GaN base LED epitaxial slice and preparation method thereof - Google Patents
A kind of GaN base LED epitaxial slice and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a kind of GaN base LED epitaxial slice and preparation method thereof, belong to technical field of semiconductors.Epitaxial wafer comprises substrate and the GaN nucleating layer grown successively on substrate, plain GaN layer, n-layer, multiple quantum well layer and p-type layer, multiple quantum well layer is multicycle structure, each cycle comprises InGaN layer and GaN layer, the cycle contacted with n-layer of multicycle structure is the period 1, the GaN layer δ of period 1 is doped with Si, and the Si of the GaN layer of period 1 is entrained in the position away from first-phase adjacent bed, first-phase adjacent bed is the InGaN layer contacted with the GaN layer of period 1.The present invention, by such scheme, can reduce the dislocation in multiple quantum well layer, the impact of shielding polarized electric field, improve crystal mass, Si can not be diffused in InGaN layer, can avoid forming point defect in multiple quantum well layer, make the combined efficiency in electronics and hole high, luminous efficiency is high.
Description
Technical field
The present invention relates to technical field of semiconductors, particularly a kind of GaN base LED epitaxial slice and preparation method thereof.
Background technology
GaN (gallium nitride) is the Typical Representative in third generation semiconductor material with wide forbidden band, and the physics and chemistry characteristic of its excellence makes it have very great application prospect in the field such as microelectronic component and opto-electronic device.In microelectronic component, GaN relies on its stable physicochemical properties to be widely used in making the microelectronic components such as High Electron Mobility Transistor, SAW (Surface Acoustic Wave) device and Gunn effect microwave device.
Existing GaN base LED epitaxial slice generally comprises substrate and is sequentially laminated on the GaN nucleating layer on substrate, plain GaN layer, n-layer, multiple quantum well layer and p-type layer, wherein, multiple quantum well layer is generally by InGaN layer and GaN layer is alternately laminated successively forms.When growing multiple quantum well layer, be generally adopt low-temperature epitaxy GaN layer, the growth temperature that GaN layer is lower, makes produce dislocation between GaN layer and InGaN layer, causes the interface of GaN layer and InGaN layer smooth not, reduce the crystal mass of multiple quantum well layer.In prior art, in order to reduce dislocation, generally can at whole GaN layer doping Si.
Realizing in process of the present invention, inventor finds that prior art at least exists following problem:
Adulterate in prior art Si in whole GaN layer, although can improve crystal mass to a certain extent, Si can expand to InGaN layer from GaN layer, makes multiple quantum well layer form point defect, and then reduce the combined efficiency in electronics and hole, cause the luminous efficiency of light-emitting diode low.
Summary of the invention
In order to solve the problem of prior art, embodiments provide a kind of GaN base Light-emitting Diode And Its Making Method.Described technical scheme is as follows:
On the one hand, embodiments provide a kind of LED epitaxial slice, described epitaxial wafer comprises: substrate, and the GaN nucleating layer grown successively over the substrate, plain GaN layer, n-layer, multiple quantum well layer and p-type layer, described multiple quantum well layer is multicycle structure, each cycle comprises InGaN layer and GaN layer, the cycle contacted with described n-layer of described multicycle structure is the period 1, the GaN layer δ of described period 1 is doped with Si, and the Si of the GaN layer of described period 1 is entrained in the position away from first-phase adjacent bed, described first-phase adjacent bed is the InGaN layer contacted with the GaN layer of described period 1.
Preferably, with the equal δ of GaN layer in described period 1 in several cycles of continuous print doped with Si, and the Si of the GaN layer in several cycles described is entrained in the position away from second-phase adjacent bed respectively, described second-phase adjacent bed is the InGaN layer contacted with the GaN layer in each cycle in several cycles described.
Further, in the consecutive periods of described period 1 and several cycles described composition, the Si content of each GaN layer successively decreases from bottom to up.
Further, in described multicycle structure, the GaN layer at least one cycle undopes Si.
Further, in described consecutive periods, the content of the In component of each InGaN layer increases progressively from bottom to up.
Preferably, in described consecutive periods, the thickness of the Si of the GaN layer in each cycle is 1 ~ 5nm.
Preferably, in described consecutive periods, the doping content of the Si of the GaN layer in each cycle is 0 ~ 1 × 10
20/ cm
3.
On the other hand, the embodiment of the present invention additionally provides a kind of manufacture method of GaN base LED epitaxial slice, and described method comprises:
One substrate is provided;
Growing GaN nucleating layer, plain GaN layer, n-layer successively over the substrate;
Grow multiple quantum well layer on said n-type layer, described multiple quantum well layer is multicycle structure, and each cycle comprises InGaN layer and GaN layer; The cycle contacted with described n-layer of described multicycle structure is the period 1, when growing the GaN layer of described period 1, the δ doping of elements Si is carried out in the GaN layer of described period 1, and the Si of the GaN layer of described period 1 is entrained in the position away from first-phase adjacent bed, described first-phase adjacent bed is the InGaN layer contacted with the GaN layer of described period 1;
Described multiple quantum well layer grows p-type layer.
Preferably, when growing the GaN layer with described period 1 in several cycles of continuous print, the δ doping of elements Si is carried out respectively in the GaN layer in several cycles described, and the Si of the GaN layer in several cycles described is entrained in the position away from second-phase adjacent bed respectively, described second-phase adjacent bed is the InGaN layer contacted with the GaN layer in each cycle in several cycles described.
Further, in the consecutive periods of described period 1 and several cycles described composition, the Si content of each GaN layer successively decreases from bottom to up.
The beneficial effect that the technical scheme that the embodiment of the present invention provides is brought is:
In multiple quantum well layer multicycle structure, the GaN layer δ of the period 1 contacted with n-layer is doped with Si, the Si of doping can reduce the dislocation in multiple quantum well layer, the impact of shielding polarized electric field, improve crystal mass, and be entrained in the position away from first-phase adjacent bed due to the Si of the GaN layer in the period 1, first-phase adjacent bed is the InGaN layer contacted with the GaN layer of period 1, therefore Si can not be diffused in InGaN layer, this can be avoided forming point defect in multiple quantum well layer, make the combined efficiency in electronics and hole high, the luminous efficiency of light-emitting diode is high.
Accompanying drawing explanation
In order to be illustrated more clearly in the technical scheme in the embodiment of the present invention, below the accompanying drawing used required in describing embodiment is briefly described, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the structural representation of a kind of GaN base LED epitaxial slice that the embodiment of the present invention one provides;
Fig. 2 is the energy band diagram of the first composition of the multiple quantum well layer that the embodiment of the present invention one provides;
Fig. 3 is the energy band diagram of the second composition of the multiple quantum well layer that the embodiment of the present invention one provides;
Fig. 4 is the flow chart of the manufacture method of a kind of GaN base LED epitaxial slice that the embodiment of the present invention two provides.
Embodiment
For making the object, technical solutions and advantages of the present invention clearly, below in conjunction with accompanying drawing, embodiment of the present invention is described further in detail.
Embodiment one
Embodiments provide a kind of GaN base LED epitaxial slice, this epitaxial wafer is particularly useful for the light-emitting diode making blue green light.
As shown in Figure 1, this epitaxial wafer comprises: substrate 11 and the GaN nucleating layer 12 grown successively on the substrate 11, plain GaN layer 13, n-layer 14, multiple quantum well layer and p-type layer 16, multiple quantum well layer is multicycle structure, in the present embodiment, multicycle structure comprises n cycle, be respectively the period 1 51, second round 52, period 3 53 ..., the n-th cycle 5n.Each cycle comprises InGaN layer 5a and GaN layer 5b.The cycle contacted with n-layer 14 of multicycle structure is the period 1 51, the GaN layer 5b δ of period 1 51 is doped with Si, and the Si of the GaN layer 5b of period 1 51 is entrained in the position away from first-phase adjacent bed, first-phase adjacent bed is the InGaN layer contacted with the GaN layer 5b of period 1 51, and namely first-phase adjacent bed is InGaN layer 5a and the InGaN layer 5a of second round 52 of period 1 51.
Particularly, in each cycle of multiple quantum well layer, can be that GaN layer is located in InGaN layer, also can be that InGaN layer is located in GaN layer.
In addition, Si is entrained in the position away from first-phase adjacent bed, therefore Si can not be diffused in InGaN layer 5a, this can be avoided forming point defect in multiple quantum well layer, the non-radiative recombination probability in electronics or hole is reduced greatly, the combined efficiency in electronics and hole is high, and the luminous efficiency of light-emitting diode is high.
Preferably, in the present embodiment, with the equal δ of GaN layer 5b in period 1 51 in several cycles of continuous print doped with Si, and the Si of the GaN layer 5b in these several cycles is entrained in the position away from second-phase adjacent bed respectively, second-phase adjacent bed is the InGaN layer 5a contacted with the GaN layer 5b in each cycle in these several cycles.Such as, see Fig. 1, the equal δ of GaN layer 5b of period 1 51 to period 5 55 is doped with Si, then second-phase adjacent bed is InGaN layer 5a, the InGaN layer 5a of period 3 53 of second round 52, the InGaN layer 5a of period 4 54, the InGaN layer 5a of period 5 55 and the InGaN layer 5a of period 6 56.By at the equal δ of GaN layer 5b with period 1 51 in several cycles of continuous print doped with Si, the dislocation between InGaN layer 5a in several cycles of continuous print and GaN layer 5b can be reduced, improve crystal mass further.
Further, in the present embodiment, in the consecutive periods that period 1 51 and these several cycles form, the Si content of each GaN layer 5b successively decreases from bottom to up.In the present embodiment, direction from bottom to up, refers to the direction from n-layer 14 to p-type layer 16.Such as, the equal δ of GaN layer 5b of period 1 51 to period 5 55 is doped with Si, and the Si content of the GaN layer 5b of period 1 51 to period 5 55 successively decreases from bottom to up.In this continuous print cycle, the amount of each GaN layer 5b doping Si is successively decreased from bottom to up, electronics potential well can be formed in multiple quantum well layer, when electronics is from n-layer 14 transition, this electronics potential well can reduce the speed of electronics, by electron-collection in multiple quantum well layer, effectively increase the electron concentration being injected into multiple quantum well layer, reduce the probability that electronics overflows to P-type layer 16; Meanwhile, the amount of doping Si is successively decreased from bottom to up, can improve the uniformity that electronics distributes in multiple quantum well layer.
Further, in multicycle structure, the GaN layer 5b at least one cycle undopes Si.Particularly, undope above cycle that cycle of Si is positioned at doping Si and close on p-type layer 16 place, like this, in the multicycle structure of multiple quantum well layer, the Si content of each GaN layer 5b successively decreases from bottom to up, until be decreased to 0, such as, in multiple quantum well layer, the GaN layer 5b of period 1 51 to period 5 55 all adulterates Si, the period 6 56, the 7th cycle 57, the 8th cycle 58 ..., the n-th cycle 5n GaN layer 5b all to undope Si.This structure is conducive to the cycle of hole by the Si that undopes, and more with the electron recombination entering multiple quantum well layer, the combined efficiency in electronics and hole is high.It should be noted that, the cycle of this Si that undopes can for one or more.
Alternatively, in above-mentioned consecutive periods (i.e. the cycle of the doping Si of multicycle structure), the content of the In component of each InGaN layer 5a is equal.
Preferably, in above-mentioned consecutive periods, the content of the In component of each InGaN layer 5a increases progressively from bottom to up.By making the content of In component increase progressively from bottom to up, the lattice mismatch of InGaN layer 5a and GaN layer 5b can be reduced like this, thus the quality of crystal can be improved.
Further, undope in the cycle of Si in multicycle structure, the content of the In component of each InGaN layer 5a is equal.
Further, in multicycle structure, in the cycle of doping Si, the content of In component of InGaN layer 5a is not more than the content of the In component of the InGaN layer 5a undoped in the cycle of Si (InGaN layer in the cycle of the Si that namely adulterates is expressed as In
xga
1-xn layer, the InGaN layer in the cycle of doping Si is expressed as In
yga
1-yduring N layer, x≤y).Such as, periodicity in multiple quantum well layer is 8, the GaN layer 5b of period 1 51 to period 5 55 all adulterates Si, and the content of the In component of InGaN layer 5a in period 1 51 to the period 5 55 increases progressively from bottom to up, the GaN layer 5b in period 6 56, the 7th cycle 57 and the 8th cycle 58 all undopes Si, the content of the In component of the InGaN layer 5a in the cycle 58 period 6 56 to the eight is equal, and the content of In component of InGaN layer 5a in the period 5 is equal with the content of the In component of the InGaN layer 5a in the period 6.
Particularly, in the present embodiment, multiple quantum well layer can be following structure: periodicity is 9, each cycle specifically comprise In
0.16ga
0.84n layer and GaN layer, wherein, the In in each cycle
0.16ga
0.84the thickness of N layer is the mol ratio of 2.5nm, N and Ga is 4500; The thickness of the GaN layer in each cycle is the mol ratio of 12nm, N and Ga is 4500; From bottom to up, the concentration of the GaN layer Effective Doping Si in front 5 cycles is followed successively by 1 × 10
20/ cm
3, 2 × 10
19/ cm
3, 5 × 10
18/ cm
3, 5 × 10
17/ cm
3, 1 × 10
17/ cm
3, the thickness of doping is all 1nm; The amount of Si of adulterating in GaN layer in rear four cycles is 0.The energy band diagram of the multiple quantum well layer of this structure as shown in Figure 2 (can be with and be made up of conduction band and valence band, in Fig. 2, the above is conduction band, below be valence band).The epitaxial wafer of this structure, after the semiconducter process processing procedures such as cleaning, deposition, photoetching and etching, is divided into size to be the LED chip of 10 × 8mil.LED chip is through test, and when measuring current is 20mA, single little chip optical output power is 5.6mW, and blue shift amount is 3 ~ 4nm.And traditional epitaxial wafer, the power output of single little chip light of identical chips processing procedure is 5mW, and blue shift amount is 8 ~ 12nm.Therefore, the present embodiment has the epitaxial wafer of this multiple quantum well layer epitaxial wafer traditional compared to tradition, and Multiple Quantum Well ply stress is little, electronics and hole-recombination efficiency high, the LED chip brightness of making is large.
Particularly, in the present embodiment, multiple quantum well layer also can be following structure: its periodicity is 8, and from bottom to up, front 3 each cycles in cycle comprise In
0.12ga
0.88n layer and GaN layer, the In in each cycle in first three cycle
0.12ga
0.88the thickness of N layer is the mol ratio of 2.5nm, N and Ga is 4500; In first three cycle, the thickness of the GaN layer in each cycle is the mol ratio of 12nm, N and Ga is 4500, and the concentration of the GaN layer Effective Doping Si in first three cycle is all 1 × 10
19/ cm
3, the thickness of Si doping is respectively 3nm, 2nm, 1nm; Rear 5 each cycles in cycle comprise In
0.16ga
0.84n layer and GaN layer, the In in each cycle in rear five cycles
0.16ga
0.84the thickness of N layer is the mol ratio of 2.5nm, N and Ga is 4500; The thickness of the GaN layer in each cycle in rear five cycles is the mol ratio of 12nm, N and Ga is 4500, and the amount of the GaN layer doping Si in rear five cycles is all 0.The energy band diagram of the multiple quantum well layer of this structure as shown in Figure 3 (can be with and be made up of conduction band and valence band, in Fig. 3, the above is conduction band, below be valence band).The epitaxial wafer of this structure, after the semiconducter process processing procedures such as cleaning, deposition, photoetching and etching, is divided into size to be the LED chip of 10 × 8mil.Through LED chip test, measuring current 20mA, single little chip optical output power is 5.3mW, and blue shift amount is 3 ~ 4nm.And traditional epitaxial wafer, the power output of single little chip light of identical chips processing procedure is 5mW, and blue shift amount is 8 ~ 12nm.Therefore, the present embodiment has the epitaxial wafer of this multiple quantum well layer epitaxial wafer traditional compared to tradition, and Multiple Quantum Well ply stress is little, electronics and hole-recombination efficiency high, the LED chip brightness of making is large.
Preferably, in multicycle structure, the thickness of the InGaN layer 5a in each cycle is 2 ~ 5nm, and the thickness of the GaN layer 5b in each cycle is 8 ~ 20nm.By limiting the thickness of InGaN layer 5a and GaN layer 5b, to control the thickness of multiple quantum well layer, with by the THICKNESS CONTROL of multiple quantum well layer in suitable scope, thus its growth quality can not be affected while guarantee multiple quantum well layer luminous efficiency.
Preferably, in above-mentioned consecutive periods, the thickness of the Si of the GaN layer 5b in each cycle is 1 ~ 5nm.By the thickness that control Si adulterates, thus the amount of controlled doping Si, to ensure that the amount of the Si adulterated is in appropriate scope, can reduce dislocation density on the one hand, be unlikely to again Si on the other hand and be diffused in InGaN layer 5a, cause non-radiative recombination.
Preferably, in above-mentioned consecutive periods, the doping content of the Si of the GaN layer 5b in each cycle is 0 ~ 1 × 10
20/ cm
3.The amount of doping Si is too low, and can not improve crystal mass, the amount of the Si that adulterates is too high, can bring the defect that extra doping causes, by the concentration of restriction doping Si, with the amount of controlled doping Si.
Further, by the content of In component in restriction InGaN layer 5a, can control the color of the light sent after epitaxial wafer is made into chip, preferably, in 0 ~ 0.5 scope, (namely InGaN layer 5a is In to the content of the In component of InGaN layer 5a in the present embodiment
xga
1-xn layer, 0<x<0.5), the light that now chip sends is blue green light.It should be noted that, the epitaxial wafer that the embodiment of the present invention provides, be especially suitable for the chip making blue green light.In the present embodiment, the Si of doping can shield the impact of polarized electric field, reduces the blue shift amount of wavelength.
Alternatively, in the present embodiment, substrate 11 can be Sapphire Substrate.
Alternatively, in the present embodiment, n-layer 14 can be the GaN layer of doping Si.
Alternatively, in the present embodiment, the periodicity of multiple quantum well layer is n, 4<n<12.Periodicity is too small, and affect the luminous efficiency of epitaxial wafer, periodicity is excessive, can affect the growth quality of multiple quantum well layer, increases the risk that extension length of a film is bad.
Alternatively, in the present embodiment, p-type layer 16 comprises p-type Al
yga
1-yn layer and be located at Al
yga
1-yp-type GaN layer on N layer, wherein, 0<y<0.3.Particularly, p-type Al
yga
1-yn layer can be the Al of the doped with Mg of 100nm for thickness
0.15ga
0.85n layer, wherein, p-type Al
yga
1-yin N layer, the mol ratio of N and Ga is 12000, the Mg of doping and p-type Al
yga
1-ythe mol ratio of the Ga in N layer is 1/4.P-type GaN layer can be the GaN layer of the doped with Mg of 0.4 μm for thickness, and wherein, in GaN layer, the mol ratio of N and Ga is 8000, and the mol ratio of the Ga in the Mg of doping and GaN layer is 1/80.By p-type layer 16 is comprised p-type Al
yga
1-yn layer and p-type GaN layer, p-type Al
yga
1-yn layer can block electrons, thus prevents electronics overflow.
The beneficial effect that the technical scheme that the embodiment of the present invention provides is brought is:
In multiple quantum well layer multicycle structure, the GaN layer δ of the period 1 contacted with n-layer is doped with Si, the Si of doping can reduce the dislocation in multiple quantum well layer, the impact of shielding polarized electric field, improve crystal mass, and be entrained in the position away from first-phase adjacent bed due to the Si of the GaN layer in the period 1, first-phase adjacent bed is the InGaN layer contacted with the GaN layer of period 1, therefore Si can not be diffused in InGaN layer, this can be avoided forming point defect in multiple quantum well layer, make the combined efficiency in electronics and hole high, the luminous efficiency of light-emitting diode is high; And when light-emitting diode send be blue green light time, mix the impact that Si can shield polarized electric field, reduce the blue shift amount of wavelength;
In the multicycle structure of multiple quantum well layer, the amount of each GaN layer doping Si is successively decreased from bottom to up, electronics potential well can be formed in multiple quantum well layer, when electronics is from n-layer transition, this electronics potential well can reduce the speed of electronics, by electron-collection in multiple quantum well layer, effectively increase the electron concentration being injected into multiple quantum well layer, reduce the probability that electronics overflows to P-type layer; Meanwhile, the amount of doping Si reduces from bottom to up gradually, can improve the uniformity that electronics distributes in multiple quantum well layer;
In the multicycle structure of multiple quantum well layer, the Si content of each GaN layer successively decreases from bottom to up, until be decreased to 0, be now conducive to the cycle of hole by the Si that undopes, more with the electron recombination entering multiple quantum well layer, the combined efficiency in electronics and hole is high.
Embodiment two
Embodiments provide a kind of manufacture method of GaN base LED epitaxial slice, can be used for making the GaN base LED epitaxial slice in embodiment one, see Fig. 4, the method comprises:
Step 201 a: substrate is provided;
Alternatively, in the present embodiment, substrate can be Sapphire Substrate.
Step 202: growing GaN nucleating layer, plain GaN layer, n-layer successively on substrate;
Alternatively, in the present embodiment, GaN nucleating layer grows under cryogenic, and plain GaN layer can grow under the high temperature conditions, and n-layer can be the GaN layer of doping Si.
Step 203: grow multiple quantum well layer in n-layer, multiple quantum well layer is multicycle structure, and each cycle comprises InGaN layer and GaN layer; The cycle contacted with n-layer of multicycle structure is the period 1, when growing the GaN layer of period 1, the δ doping of elements Si is carried out in the GaN layer of period 1, and the Si of the GaN layer of period 1 is entrained in the position away from first-phase adjacent bed, first-phase adjacent bed is the InGaN layer contacted with the GaN layer of period 1;
Particularly, in each cycle of multiple quantum well layer, can be that GaN layer is located in InGaN layer, also can be that InGaN layer is located in GaN layer.
Particularly, because the GaN layer of period 1 is doped with Si, and this is doped to δ doping, δ is doped to Local Gravity doping, and local refers to that part is adulterated, and namely adulterates in the part being doped material, in the present embodiment, namely refer to the part doping Si in one deck GaN layer, remaining part undopes Si, is not namely whole GaN layer doping Si; Heavy doping refers to that to mix impurity level in semi-conducting material many, is greater than every cubic centimetre has 10 as impurity concentration in Si monocrystalline reaches
18individual atom.Crystal mass can be improved by the doping of Si being set to δ doping.
In addition, Si is entrained in the position away from first-phase adjacent bed, and therefore Si can not be diffused into InGaN layer, this can be avoided forming point defect in multiple quantum well layer, the non-radiative recombination probability in electronics and hole is reduced greatly, and the combined efficiency in electronics and hole is high, and the luminous efficiency of light-emitting diode is high.
Preferably, when growing the GaN layer with period 1 in several cycles of continuous print, the δ doping of elements Si is carried out respectively in the GaN layer in these several cycles, and the Si of the GaN layer in these several cycles is entrained in the position away from second-phase adjacent bed respectively, second-phase adjacent bed is the InGaN layer contacted with the GaN layer in each cycle in these several cycles, such as, when growing with continuous print second round period 1 to the period 5, the equal δ of GaN layer of period 1 to period 5 is doped with Si, then second-phase adjacent bed is the InGaN layer of second round, the InGaN layer of period 3, the InGaN layer of period 4, the InGaN layer of period 5 and the InGaN layer of period 6.By at the equal δ of GaN layer with period 1 in several cycles of continuous print doped with Si, the dislocation between InGaN layer in several cycles of continuous print and GaN layer can be reduced, improve crystal mass further.
Further, in the consecutive periods of period 1 and this several cycle composition, the Si content of each GaN layer successively decreases from bottom to up.In the present embodiment, direction from bottom to up, refers to the direction from n-layer to p-type layer.Such as, when growing period 1 to the period 5, the Si content of the GaN layer of period 1 to period 5 successively decreases from bottom to up.In this continuous print cycle, the amount of each GaN layer doping Si is successively decreased from bottom to up, electronics potential well can be formed in multiple quantum well layer, when electronics is from n-layer transition, this electronics potential well can reduce the speed of electronics, by electron-collection in multiple quantum well layer, effectively increase the electron concentration being injected into multiple quantum well layer, reduce the probability that electronics overflows to P-type layer; Meanwhile, the amount of doping Si is successively decreased from bottom to up, can improve the uniformity that electronics distributes in multiple quantum well layer.
Further, in multicycle structure, the GaN layer at least one cycle undopes Si.Particularly, undope above cycle that cycle of Si is positioned at doping Si and close on p-type layer place, like this, in the multicycle structure of multiple quantum well layer, the Si content of each GaN layer successively decreases from bottom to up, until be decreased to 0, such as, periodicity in multiple quantum well layer is 8, and the GaN layer of period 1 to period 5 is all adulterated Si, and the GaN layer in period 6 to the 8th cycle all undopes Si.This structure is conducive to the cycle of hole by the Si that undopes, and more with the electron recombination entering multiple quantum well layer, the combined efficiency in electronics and hole is high.It should be noted that, the cycle of this Si that undopes can for one or more.
Alternatively, in above-mentioned consecutive periods (i.e. the cycle of the doping Si of multicycle structure), the content of the In component of each InGaN layer 5a is equal.
Preferably, in above-mentioned consecutive periods, the content of the In component of each InGaN layer 5a increases progressively from bottom to up.By making the content of In component increase progressively from bottom to up, the lattice mismatch of InGaN layer 5a and GaN layer 5b can be reduced like this, thus the quality of crystal can be improved.
Further, undope in the cycle of Si in multicycle structure, the content of the In component of each InGaN layer 5a is equal.
Further, in multicycle structure, in the cycle of doping Si, the content of In component of InGaN layer 5a is not more than the content of the In component of the InGaN layer 5a undoped in the cycle of Si (InGaN layer in the cycle of the Si that namely adulterates is expressed as In
xga
1-xn layer, the InGaN layer in the cycle of doping Si is expressed as In
yga
1-yduring N layer, x≤y).Such as, periodicity in multiple quantum well layer is 8, the GaN layer of period 1 to period 5 is all adulterated Si, and the period 1 increases progressively from bottom to up to the content of the In component of the InGaN layer in the period 5, the GaN layer in period 6, the 7th cycle and the 8th cycle all undopes Si, period 6 is constant to the content of the In component of the InGaN layer in the 8th cycle, and the content of In component of InGaN layer in the period 5 is equal with the content of the In component of the InGaN layer in the period 6.
Preferably, in multicycle structure, the thickness of the InGaN layer in each cycle is 2 ~ 5nm, and the thickness of the GaN layer in each cycle is 8 ~ 20nm.By restriction InGaN layer and the thickness of GaN layer, to control the thickness of multiple quantum well layer, with by the THICKNESS CONTROL of multiple quantum well layer in suitable scope, thus its growth quality can not be affected while guarantee multiple quantum well layer luminous efficiency.
Preferably, in above-mentioned consecutive periods, the thickness of the Si doping of the GaN layer in each cycle is 1 ~ 5nm.By the thickness that control Si adulterates, thus the amount of controlled doping Si, to ensure that the Si adulterated is in appropriate scope, can reduce dislocation density on the one hand, be unlikely to again Si on the other hand and be diffused in InGaN layer, cause non-radiative recombination.
Preferably, in above-mentioned consecutive periods, the doping content of the Si of the GaN layer in each cycle is 0 ~ 1 × 10
20/ cm
3.The amount of doping Si is too low, and can not improve crystal mass, the amount of the Si that adulterates is too high, can bring the defect that extra doping causes.By the concentration of restriction doping Si, with the amount of controlled doping Si.
Further, by limiting the content of the In component of InGaN layer 5a, can control the color of the light sent after epitaxial wafer is made into chip, preferably, in the present embodiment InGaN layer 5a, in 0 ~ 0.5 scope, (namely InGaN layer 5a is In to the content of In component
xga
1-xn layer, 0<x<0.5), the light that now chip sends is blue green light.It should be noted that the epitaxial slice structure that the embodiment of the present invention provides, be especially suitable for the chip making blue green light.In the present embodiment, the Si of doping can shield the impact of polarized electric field, reduces the blue shift amount of wavelength.
Alternatively, in the present embodiment, the periodicity of multiple quantum well layer is n, 4<n<12.Periodicity is too small, and affect the luminous efficiency of epitaxial wafer, periodicity is excessive, can affect the growth quality of multiple quantum well layer, increases the risk that extension length of a film is bad.
Step 204: grow p-type layer on multiple quantum well layer;
Alternatively, in the present embodiment, p-type layer comprises p-type Al
yga
1-yn layer and be located at p-type Al
yga
1-yp-type GaN layer on N layer, wherein, 0<y<0.3.By p-type layer is comprised p-type Al
yga
1-yn layer and p-type GaN layer, p-type Al
yga
1-yn layer can block electrons, thus prevents electronics overflow.
Particularly, step 201 ~ 204 can be realized by following steps:
(1) provide Sapphire Substrate, and be 1200 DEG C by Sapphire Substrate in temperature, anneal in pure hydrogen atmosphere, then cool to 600 DEG C and carry out nitrogen treatment;
(2) at 600 DEG C, the GaN nucleating layer that growth 20nm is thick, during this growth course, growth pressure is the mol ratio of 420Torr, N and Ga is 900;
(3), after the growth of GaN nucleating layer terminates, stop passing into TMGa, underlayer temperature is raised 1220 DEG C, carry out annealing in process in position to GaN nucleating layer, annealing time is 8 minutes; After annealing, temperature is adjusted to 1220 DEG C, under the molar ratio of lower N and Ga, epitaxial growth thickness is the plain GaN layer of 3 μm, and in this growth course, growth pressure is 1500 in the mol ratio of 200Torr, N and Ga;
(4) after plain GaN layer growth terminates, growth one deck doping content 1 × 10
18/ cm
3n-type GaN layer, thickness is 2 μm, and growth temperature is 1220 DEG C, and growth pressure is the mol ratio of 150Torr, N and Ga is 1800;
(5) in n-type GaN layer, first grow the Multiple Quantum Well in 5 cycles, each cycle comprises In
0.16ga
0.84n layer and GaN layer, In
0.16ga
0.84the thickness of N layer is 2.5nm, and growth temperature is 780 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500; The thickness 12nm of GaN layer, growth temperature is 900 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500, and in GaN layer, the thickness of Si doping is that the Effective Doping concentration of 1nm, Si is for being followed successively by 1 × 10
20/ cm
3, 2 × 10
19/ cm
3, 5 × 10
18/ cm
3, 5 × 10
17/ cm
3, 1 × 10
17/ cm
3; Regrowth 4 cycle multiple quantum well layers, each cycle comprises In
0.16ga
0.84n layer and GaN Multiple Quantum Well, In
0.16ga
0.84the thickness of N layer is 2.5nm, and growth temperature is 780 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500; The amount of Si of adulterating in GaN layer is 0, and the thickness 12nm of GaN layer, growth temperature is 900 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500.
(6), after multiple quantum well layer growth terminates, raise temperature, temperature controls at 1020 DEG C, and growth pressure is the mol ratio of 300Torr, N and Ga is 12000, and growth thickness is the P type Al of 100nm
0.15ga
0.85n layer.This layer of Mg doping content is higher, and the mol ratio of Mg and Ga is 1/4.Then at P type Al
0.15ga
0.85the P type GaN layer that the upper growth of N 0.4 μm is thick, its growth temperature 1000 DEG C, mol ratio 8000, Mg and the Ga mol ratio of growth pressure 200Torr, N and Ga is 1/80.
After all epitaxial growths terminate, the temperature of reaction chamber is down to 800 DEG C, pure nitrogen gas atmosphere carries out annealing in process 10min, is then down to room temperature, terminates epitaxial growth.
Apparently, above-mentioned steps (5) also can be replaced by following steps:
N-type GaN layer first grows the multiple quantum well layer in 3 cycles, and each cycle comprises In
0.12ga
0.88n layer and GaN layer, In
0.12ga
0.88the thickness of N layer is 2.5nm, and growth temperature is 780 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500; The thickness 12nm of GaN layer, growth temperature is 900 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500, and the thickness of doping is respectively 3nm, 2nm, 1nm, and the Effective Doping concentration of Si is 1 × 10
19/ cm
3; The multiple quantum well layer in 5 cycles of regrowth, each cycle comprises In
0.16ga
0.84the GaN layer of N layer and the Si that do not adulterate, In
0.16ga
0.84the thickness of N is 2.5nm, and growth temperature is 780 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500; Do not adulterate the thickness 12nm of GaN layer of Si, and growth temperature is 900 DEG C, and growth pressure is the mol ratio of 200Torr, N and Ga is 4500.
The beneficial effect that the technical scheme that the embodiment of the present invention provides is brought is: in multiple quantum well layer multicycle structure, the GaN layer δ of the period 1 contacted with n-layer is doped with Si, the Si of doping can reduce the dislocation in multiple quantum well layer, the impact of shielding polarized electric field, improve crystal mass, and be entrained in the position away from first-phase adjacent bed due to the Si of the GaN layer in the period 1, first-phase adjacent bed is the InGaN layer contacted with the GaN layer of period 1, therefore Si can not be diffused in InGaN layer, this can be avoided forming point defect in multiple quantum well layer, make the combined efficiency in electronics and hole high, the luminous efficiency of light-emitting diode is high, and when light-emitting diode send be blue green light time, mix the impact that Si can shield polarized electric field, reduce the blue shift amount of wavelength,
In the multicycle structure of multiple quantum well layer, the amount of each GaN layer doping Si is successively decreased from bottom to up, electronics potential well can be formed in multiple quantum well layer, when electronics is from n-layer transition, this electronics potential well can reduce the speed of electronics, by electron-collection in multiple quantum well layer, effectively increase the electron concentration being injected into multiple quantum well layer, reduce the probability that electronics overflows to P-type layer; Meanwhile, the amount of doping Si reduces from bottom to up gradually, can improve the uniformity that electronics distributes in multiple quantum well layer;
In the multicycle structure of multiple quantum well layer, the Si content of each GaN layer successively decreases from bottom to up, until be decreased to 0, be now conducive to the cycle of hole by the Si that undopes, more with the electron recombination entering multiple quantum well layer, the combined efficiency in electronics and hole is high.
The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.
These are only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (10)
1. a GaN base LED epitaxial slice, described epitaxial wafer comprises substrate, and the GaN nucleating layer grown successively over the substrate, plain GaN layer, n-layer, multiple quantum well layer and p-type layer, described multiple quantum well layer is multicycle structure, each cycle comprises InGaN layer and GaN layer, it is characterized in that, the cycle contacted with described n-layer of described multicycle structure is the period 1, the GaN layer δ of described period 1 is doped with Si, and the Si of the GaN layer of described period 1 is entrained in the position away from first-phase adjacent bed, described first-phase adjacent bed is the InGaN layer contacted with the GaN layer of described period 1.
2. epitaxial wafer according to claim 1, it is characterized in that, with the equal δ of GaN layer in described period 1 in several cycles of continuous print doped with Si, and the Si of the GaN layer in several cycles described is entrained in the position away from second-phase adjacent bed respectively, described second-phase adjacent bed is the InGaN layer contacted with the GaN layer in each cycle in several cycles described.
3. epitaxial wafer according to claim 2, is characterized in that, in the consecutive periods of described period 1 and several cycles described composition, the Si content of each GaN layer successively decreases from bottom to up.
4. epitaxial wafer according to claim 3, is characterized in that, in described multicycle structure, the GaN layer at least one cycle undopes Si.
5. epitaxial wafer according to claim 4, is characterized in that, in described consecutive periods, the content of the In component of each InGaN layer increases progressively from bottom to up.
6. epitaxial wafer according to claim 5, is characterized in that, in described consecutive periods, the thickness of the Si of the GaN layer in each cycle is 1 ~ 5nm.
7. the epitaxial wafer according to any one of claim 3-6, is characterized in that, in described consecutive periods, the doping content of the Si of the GaN layer in each cycle is 0 ~ 1 × 10
20/ cm
3.
8. a manufacture method for GaN base LED epitaxial slice, described method comprises:
One substrate is provided;
Growing GaN nucleating layer, plain GaN layer, n-layer successively over the substrate;
Grow multiple quantum well layer on said n-type layer, described multiple quantum well layer is multicycle structure, and each cycle comprises InGaN layer and GaN layer;
Described multiple quantum well layer grows p-type layer,
It is characterized in that, the cycle contacted with described n-layer of described multicycle structure is the period 1, when growing the GaN layer of described period 1, the δ doping of elements Si is carried out in the GaN layer of described period 1, and the Si of the GaN layer of described period 1 is entrained in the position away from first-phase adjacent bed, described first-phase adjacent bed is the InGaN layer contacted with the GaN layer of described period 1.
9. method according to claim 8, it is characterized in that, when growing the GaN layer with described period 1 in several cycles of continuous print, the δ doping of elements Si is carried out respectively in the GaN layer in several cycles described, and the Si of the GaN layer in several cycles described is entrained in the position away from second-phase adjacent bed respectively, described second-phase adjacent bed is the InGaN layer contacted with the GaN layer in each cycle in several cycles described.
10. method according to claim 9, is characterized in that, in the consecutive periods of described period 1 and several cycles described composition, the Si content of each GaN layer successively decreases from bottom to up.
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