CN103258923A - Quantum well barrier layer growing method for improving CaN-based LED light-emitting efficiency - Google Patents

Abstract

The invention discloses a quantum well barrier layer growing method for improving CaN-based LED light-emitting efficiency. A plurality of quantum wells of a light-emitting layer in an LED epitaxial slice comprise low-temperature shallow quantum wells and low-temperature multiple quantum wells from top to bottom in sequence. Barrier layers of the low-temperature multiple quantum wells grow in a high growth rate, and temperature difference of the barrier quantum wells is kept at about 130 DEG C, and the quantum wells all grow in a high pressure which is higher than 200Torr. The specific growing method includes the steps that a first quantum well barrier layer enters a TMGa source to replace a TEGa source; a second quantum well barrier layer replaces the TEGa source by a TMGa source, and the inlet amount of the TMGa is doubled in order to improve a growth rate; a third quantum well barrier layer is doubled after the TMGa source is added, in order to maintain the thickness of the entire quantum well barrier layer cycle to be constant, the barrier layer growing time is reduced by a half correspondingly. By means of the method, quantum well structure CaN-based materials with high crystal quality and high light-emitting efficiency and CaN LEDs with high light-emitting strength are effectively obtained.

Description

A kind of quantum well of GaN base LED luminous efficiency is built the layer growth method

 

Technical field

The present invention relates to GaN based material preparing technical field, more particularly, the quantum well that relates to a kind of GaN base LED luminous efficiency is built the layer growth method.

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Background technology

The GaN(gallium nitride) sill is ionic crystals, because positive and negative charge does not overlap, forms spontaneous polarization.In addition, because the InGaN(InGaN) and the GaN material between lattice adaptive, can cause piezoelectric polarization again, and then form piezoelectric polarization fields.The existence of polarization field makes the equivalent energy gap of quantum well reduce the emission wavelength red shift on the one hand; The overlapping meeting of electronics and hole wave function reduces on the other hand, reduces its radiation recombination probability.

Influence the another one reason of quantum well radiation efficient: N district injected electrons has very big carrier mobility and concentration, under the driving of big electric current, can cross the hole-recombination in quantum well region and P district, cause non-radiative compound, make the reduction of luminous efficiency, and the effective mass in hole is bigger, and its mobility and carrier concentration are all lower, away from the hole distribution in P district seldom, whole well region hole distribution is very inhomogeneous, causes the radiation recombination probability to descend.

For the optimization of electron concentration, mainly used the Electron Extended layer at present, methods such as electronic barrier layer and the asymmetric resonant tunneling structure of electric charge have been used the less methods such as last one deck base of thickness in the distribution in hole.Said method has improved the radiation recombination efficient of quantum well to a certain extent, but effect is limited.

 

Summary of the invention

The present invention is directed to above-mentioned problems of the prior art, provide a kind of quantum well of the GaN of raising base LED luminous efficiency to build the layer growth method, can effectively obtain the quantum well structure gallium nitride-based material of high crystalline quality, high-luminous-efficiency, obtain the GaN series LED of high luminous intensity.

For achieving the above object, the technical solution adopted in the present invention is as follows:

A kind of quantum well that improves GaN base LED luminous efficiency is built the layer growth method, and this LED epitaxial slice structure order from bottom to top is followed successively by: substrate layer, low temperature GaN resilient coating, unadulterated high temperature GaN resilient coating, Si doped n type GaN layer, luminescent layer Multiple Quantum Well, low temperature p-type GaN layer, p-type AlGaN electronic barrier layer, high temperature p-type GaN layer, p-type GaN contact layer; The luminescent layer Multiple Quantum Well comprises the shallow quantum well of low temperature, low temperature multiple quantum well light emitting layer structure from the bottom up successively; Wherein low temperature Multiple Quantum Well base layer adopts high growth rates growth and the base trap temperature difference to remain on about 130 ℃, and quantum well all adopts high pressure to grow greater than 200Torr, and specifically growing method is: first quantum well is built layer and is fed a replacement TEGa source, a TMGa source; After second quantum well base layer replaces TEGa with TMGa, for improving growth rate feeding amount in TMGa source is doubled; The third base layer feeds after the TMGa source doubles, and is constant for keeping whole quantum well layer periodic thickness, correspondingly will build the layer growth time and reduce by half.

The growing method of LED light emitting diode epitaxial structure provided by the present invention can effectively reduce the defect concentration of quantum well region, adjusts the PN junction position, improves electronics and hole at the combined efficiency of luminescent quantum well region.In addition, quantum well is built the polarity effect of Light-Emitting Diode active area is reduced, and it is luminous to make electronics and hole can use up many band edge radiation recombination of being open to the custom in quantum well, reaches the effect of the luminous efficiency that improves light-emitting diode.

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Description of drawings

Fig. 1 is LED epitaxial structure schematic diagram provided by the present invention;

Fig. 2 is that the quantum well trap is built marked graph among Fig. 1.

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Embodiment

Below embodiments of the invention are elaborated: present embodiment is being to implement under the prerequisite with the technical solution of the present invention, provided detailed execution mode and concrete operating process, but protection scope of the present invention is not limited to following embodiment.

LED epitaxial structure as shown in Figure 1 comprises:substrate layer 1, low temperature GaNresilient coating 2, unadulterated high temperature GaN resilient coating 3, Si Doped n-type GaN layer 4, shallowquantum well 5, luminescent layerMultiple Quantum Well 6, low temperature p type GaN layer 7, p type AlGaN electronic barrier layer 8, high temperature ptype GaN layer 9, p typeGaN contact layer 10.

Provided by the present inventionly improve the shallow quantum trap growth structure of GaN base LED to improve the concrete implementation step of method of luminous efficiency as follows:

Substrate layer 1 was annealed inhydrogen atmosphere 1～10 minute, clean described substrate surface, temperature is controlled between 1050～1080 ℃, carries out nitrogen treatment then.Described substrate is the material that is fit to GaN and the growth of semiconductor epitaxial material thereof, as sapphire, and GaN monocrystalline, monocrystalline silicon, single-crystal silicon carbide etc.

Temperature is dropped between 450 ℃～650 ℃, the thick low temperature GaNresilient coating 2 of growth 15～35nm, during this growth course, growth pressure is controlled between 400～760 Torr, and V/III mol ratio is between 500～3200.

Behind described low temperature GaN resilient coating 2 growth endings, its original position is carried out thermal anneal process, stop to feed TMGa, underlayer temperature is increased between 950～1200 ℃, annealing time is between 5 minutes to 10 minutes.After the annealing, with between adjustment to 1000～1200 ℃, growth thickness is the unadulterated high temperature GaN resilient coating 3 between 0.8um～4um, and during this growth course, growth pressure is between 100Torr～600 Torr, and V/III mol ratio is between 300～3300.

Behind described unadulterated high temperature GaN resilient coating 3 growth endings, growth one deck Si doping content stable n-type GaN layer 4, thickness is at 1.0～5.0um, and growth temperature is between 1000 ℃～1200 ℃, growth pressure is between 50～550 Torr, and V/III mol ratio is between 300～3300.

Behind described Si doped ntype GaN layer 4 growth ending, growth is by the In in 5-15 cycle_xGa_1-XThe shallowquantum well layer 5 that the Multiple Quantum Well that N (0.04＜x＜0.4)/GaN forms is formed, the thickness of described shallowquantum well layer 5 is between 3nm-5nm, growth temperature is between 720 ℃-920 ℃, and pressure is between 100Torr-600 Torr, and V/III mol ratio is between 300-5000.

Behind shallowquantum well layer 5 growth endings of described low temperature, beginning growing low temperature luminescent layerMultiple Quantum Well 6 structures, the chemiluminescence layerMultiple Quantum Well 6 InyGa1～yN by 3～15 cycles (x＜y＜1)/GaN Multiple Quantum Well is formed.As shown in Figure 2, wherein the growth pattern of trap 6-a is the class tapered in form, the component of In remains unchanged, between 10%～50%, the thickness of trap is between 2nm～5nm, growth temperature is between 720 ℃～820 ℃, and growth pressure is between 200Torr～500 Torr, and V/III mol ratio is between 400～5300.The low temperature Multiple Quantum Well is built layer 6-b and is adopted high growth rates growth and the base trap temperature difference to remain on about 130 ℃, build layer growth pressure with trap layer growth pressure, between 200Torr～500 Torr, concrete growing method is: first quantum well is built layer and is fed the TEGa source that the TMGa source replaces conventional growth method to feed; Second quantum well is built layer and is replaced for improving growth rate feeding amount in TMGa source being doubled behind the TEGa with TMGa; The third base layer feeds the TMGa source, and to double the back constant for keeping whole quantum well layer periodic thickness, and need are corresponding will be built the layer growth time and reduce by half.The growth temperature that all quantum are built is between 850～950 ℃, and pressure is between 200Torr～500 Torr, and V/III mol ratio is between 400～5300.

Behind described luminescent layer multiplequantum well layer 6 growth endings, low temperature p type GaN layer 7 between growth thickness 10nm～100nm, growth temperature is between 500 ℃～800 ℃, growth time is between 5 minutes～20 minutes, pressure is between 100Torr～500 Torr, and V/III mol ratio is between 300～5300.In the process of growing low temperature p type GaN layer 7, N2 is as carrier gas, doped dielectric two luxuriant magnesium.

After described low temperature p type GaN layer 7 finishes, temperature is risen between 900 ℃～1100 ℃, growth pressure is between 50Torr～400 Torr, growth time is between 5 minutes～15 minutes, p type AlGaN electronic barrier layer 8 between growth thickness 10nm～100nm, V/III mol ratio is between 1000～20000, the component control of Al is between 15%～40%, the energy gap that P type AlGaN electronic barrier layer 8 energy gaps are built greater than last quantum, P type AlGaN electronic barrier layer 8 energy gaps can be controlled between 4ev and the 5.5ev.

Behind described p type AlGaN electronic barrier layer 8 growth endings, the high temperature ptype GaN layer 9 between a layer thickness 0.1 um～0.9 um of growing, its growth temperature is between 850～1090 ℃.

Behind described high temperature p-type GaN layer 9 growth ending, grow p typeGaN contact layer 10 between the layer thickness 5nm～30nm, its growth temperature is between 850 ℃～1050 ℃, between the pressure, growth pressure between 100Torr～450Torr, growth time between 5～20min, V/III mol ratio in 300～50 power between 100Torr～500Torr, growth time is between 1～10min, and V/III mol ratio is between 1000～20000.

Epitaxial growth is down to the temperature of reative cell between 650 ℃～800 ℃ after finishing, and adopts annealing inprocess 5 min～15min in the pure nitrogen gas atmosphere, is down to room temperature then, finishes epitaxial growth.Epitaxial wafer to growth cleans then, semiconducter process such as deposition, photoetching and etching make single small size chip.

Present embodiment with high-purity hydrogen or nitrogen as carrier gas, with trimethyl gallium (TMGa), triethyl-gallium (TEGa), trimethyl aluminium (TMAl), trimethyl indium (TMIn) and ammonia (NH3) use silane (SiH4) and two luxuriant magnesium (Cp2Mg) respectively as n, p-type dopant respectively as Ga, Al, In and N source.

The above only is preferred embodiment of the present invention, not in order to limiting the present invention, all any modifications of doing within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims (10)

1. a quantum well that improves GaN base LED luminous efficiency is built the layer growth method, and this LED epitaxial slice structure order from bottom to top is followed successively by: substrate layer, low temperature GaN resilient coating, unadulterated high temperature GaN resilient coating, Si doped n type GaN layer, luminescent layer Multiple Quantum Well, low temperature p-type GaN layer, p-type AlGaN electronic barrier layer, high temperature p-type GaN layer, p-type GaN contact layer; The luminescent layer Multiple Quantum Well comprises the shallow quantum well of low temperature, low temperature multiple quantum well light emitting layer structure from the bottom up successively; It is characterized in that, wherein the low temperature Multiple Quantum Well is built layer employing high growth rates growth and is built the trap temperature difference and remains on about 130 ℃, quantum well all adopts high pressure to grow greater than 200Torr, and concrete growing method is: first quantum well is built layer and is fed replacement TEGa source, TMGa source; After second quantum well base layer replaces TEGa with TMGa, for improving growth rate feeding amount in TMGa source is doubled; The third base layer feeds after the TMGa source doubles, and is constant for keeping whole quantum well layer periodic thickness, correspondingly will build the layer growth time and reduce by half.

2. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 1 is built the layer growth method, it is characterized in that, the growing method of described substrate layer is: annealed in hydrogen atmosphere 1～10 minute, the clean substrate surface, temperature control is carried out nitrogen treatment then between 1050～1080 ℃.

3. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 2 is built the layer growth method, it is characterized in that, the growing method of described low temperature GaN resilient coating is: temperature is dropped between 450 ℃～650 ℃, pressure control is between 400～760 Torr, V/III mol ratio between 500～3200, growth 15～35nm thick GaN low temperature buffer layer.

4. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 3 is built the layer growth method, it is characterized in that, the growing method of described unadulterated high temperature GaN resilient coating is: after described low temperature GaN buffer growth finishes, its original position is carried out thermal anneal process, stop to feed TMGa, underlayer temperature is increased between 950～1200 ℃, annealing time is between 5～10min, after the annealing, with between adjustment to 1000～1200 ℃, growth thickness is the GaN resilient coating that undopes of the high temperature between 0.8um～4um, during this growth course, pressure is between 100Torr～600 Torr, and V/III mol ratio is between 300～3300.

5. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 4 is built the layer growth method, it is characterized in that, the growing method of described Si doped n type GaN layer is: after described unadulterated high temperature GaN buffer growth finishes, between 1000 ℃～1200 ℃ of growth temperatures, growth pressure is between 50～550 Torr, V/III mol ratio between 300～3300, growth one deck doping content stable n-type GaN layer

Thickness is at 1.0～5.0um.

6. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 5 is built the layer growth method, it is characterized in that the growing method that described luminescent layer Multiple Quantum Well is built layer is: comprise from the bottom up the shallow quantum well of low temperature and the low temperature multiple quantum well light emitting layer structure of growth successively; Wherein: the shallow quantum well layer of described low temperature, growth is by the In in 5-15 cycle_xGa_1-XThe shallow quantum well layer that N (0.04＜x＜0.4)/GaN forms, the thickness of described shallow quantum well is between 3nm-5nm, and growth temperature is between 720 ℃-920 ℃, and pressure is between 100Torr-600 Torr, and V/III mol ratio is between 300-5000; The growing method of described low temperature multiple quantum well light emitting layer structure is: InyGa1～yN (x＜y＜the 1)/GaN Multiple Quantum Well by 3～15 cycles is formed, wherein the growth pattern of trap is the class tapered in form, the component of In remains unchanged, between 10%～50%, the thickness of trap is between 2nm～5nm, growth temperature is between 720 ℃～820 ℃, and growth pressure is between 200Torr～500 Torr, and V/III mol ratio is between 400～5300; The low temperature Multiple Quantum Well is built layer and is adopted high growth rates growth and the base trap temperature difference to remain on about 130 ℃, builds layer growth pressure with trap layer growth pressure, between 200Torr～500 Torr; The growth temperature that all quantum are built is between 850～950 ℃, and pressure is between 200Torr～500 Torr, and V/III mol ratio is between 400～5300.

7. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 6 is built the layer growth method, it is characterized in that, the growing method of described low temperature p type GaN layer is: after low temperature multiple quantum well light emitting layer structure growth finishes, low temperature p type GaN layer between growth thickness 10nm～100nm, growth temperature is between 500 ℃～800 ℃, growth time is between 5 minutes～20 minutes, and pressure is between 100Torr～500 Torr, and V/III mol ratio is between 300～5300.

8. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 7 is built the layer growth method, it is characterized in that, the growing method of described low temperature p type AlGaN electronic barrier layer is: after described low temperature p type GaN layer growth finishes, temperature is risen between 900 ℃～1100 ℃, growth pressure is between 50Torr～400 Torr, growth time is between 5 minutes～15 minutes, the p type AlGaN electronic barrier layer of growth thickness between 10nm～100nm, V/III mol ratio is between 1000～20000, and the component of Al is controlled between 15%～40%.

9. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 8 is built the layer growth method, it is characterized in that, the growing method of described high temperature p-type GaN layer is: after described low temperature p type AlGaN layer growth finishes, grow high temperature p type GaN layer between a layer thickness 0.1 um～0.9 um, its growth temperature is between 850～1090 ℃, growth pressure between 100Torr～450 Torr, growth time 5～

Between the 20min, V/III mol ratio is between 300～5000.

10. the quantum well of raising GaN base LED luminous efficiency as claimed in claim 9 is built the layer growth method, it is characterized in that, the growing method of described p-type GaN contact layer is: after described high temperature p-type GaN layer growth finishes, grow p type GaN contact layer between the layer thickness 5nm～30nm, its growth temperature is between 850 ℃～1050 ℃, pressure is between 100Torr～500 Torr, and growth time is between 1～10min, and V/III mol ratio is between 1000～20000.

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