CN214830784U

CN214830784U - GaN single crystal substrate with stacked high-doped layer

Info

Publication number: CN214830784U
Application number: CN202023034009.4U
Authority: CN
Inventors: 顾泓; 刘宗亮; 徐科
Original assignee: Suzhou Institute of Nano Tech and Nano Bionics of CAS
Current assignee: Suzhou Institute of Nano Tech and Nano Bionics of CAS
Priority date: 2020-12-16
Filing date: 2020-12-16
Publication date: 2021-11-23
Anticipated expiration: 2030-12-16

Abstract

The utility model discloses a fold and establish gaN single crystal substrate of high doping layer. The GaN single crystal substrate with the stacked high-doped layer comprises seed crystals, and a non-doped gallium nitride layer and a high-doped gallium nitride layer which are stacked on the seed crystals, wherein the high-doped gallium nitride layer is distributed between the two non-doped gallium nitride layers. The embodiment of the utility model provides a pair of fold GaN single crystal substrate who establishes high doping layer inserts the high concentration impurity doping layer of gallium nitride crystal through periodicity, interval formula, makes the stress of non-doping gallium nitride within a definite time layer obtain effective release, has finally effectively improved the gallium nitride crystal quality of gained.

Description

GaN single crystal substrate with stacked high-doped layer

Technical Field

The utility model particularly relates to a fold and establish gaN single crystal substrate of high doping layer belongs to semiconductor technology field.

Background

In recent years, gallium nitride (GaN) materials, which are the core of the third generation semiconductors, have become ideal materials for fabricating high-temperature, high-voltage, high-frequency, high-power, radiation-resistant microelectronic devices and short-wavelength, high-power optoelectronic devices, due to their unique advantages. However, there is a huge gap in quantity and quality between the demand in the application market and the current actual supply, and it is important to develop a production technology suitable for mass production of high quality GaN substrates to develop the device industry. In this context, flux method (Na-flux) has become a research hotspot as a growth method in a near thermodynamic equilibrium state.

Compared with other growth modes, the fluxing agent method provides a method for obtaining high-quality GaN single crystal under relatively mild growth conditions, the growth rate can reach 30 mu m/h, and the feasibility of industrialized mass production is achieved. Meanwhile, in the growth of the fluxing agent, continuous and effective crystal growth can be obtained by further regulating and controlling experimental conditions such as growth temperature, pressure and the like and experimental process, and further the gallium nitride single crystal with large size and high quality can be obtained. Many research teams at home and abroad have already been invested in the research on the fluxing agent method, and the method mainly comprises the following steps: osaka university, northeast university, united states air force, navy research laboratory, and the like. At present, centimeter-level and large-size (2-6 inch) gallium nitride single crystals are successfully grown by a flux method, and the dislocation density of the single crystals can be reduced to 10 below zero²/cm²Of the order of magnitude.

On the other hand, although the flux method presents great advantages, certain problems still exist, especially in terms of stress control: in the flux method growth, generally, a homogeneous substrate such as HVPE is used as a seed material for epitaxial growth. However, even with homoepitaxial growth, as the size of the crystal increases, corresponding cracking often results and ultimately crystal fracture as a result of problems such as differences in lattice constants at the interfaces, incorporation of impurities, and thermal stress buildup. Therefore, for the industrial development of the flux method, the realization of stress control and crack-free growth is the important to be solved.

SUMMERY OF THE UTILITY MODEL

The main object of the present invention is to provide a stacked GaN single crystal substrate with a highly doped layer to overcome the stress accumulation problem of GaN single crystal substrate in the prior art.

For realizing the purpose of the utility model, the utility model discloses a technical scheme include:

the embodiment of the utility model provides a fold and establish gaN single crystal substrate of high doping layer, it includes the seed crystal and folds to be established non-doping gallium nitride layer and high doping gallium nitride layer on the seed crystal, high doping gallium nitride layer distributes two between the non-doping gallium nitride layer.

In some specific embodiments, the GaN single crystal substrate stacked with the highly doped layers includes a plurality of undoped layers and a plurality of highly doped gallium nitride layers stacked on the seed crystal in sequence, and the plurality of highly doped gallium nitride layers are distributed among the plurality of undoped layers at intervals.

In some specific embodiments, the GaN single crystal substrate stacked with the highly doped layer includes a seed crystal, and a first undoped gallium nitride layer, a highly doped gallium nitride layer, and a second undoped gallium nitride layer stacked on the seed crystal in sequence.

In some specific embodiments, the GaN single crystal substrate stacked with the highly doped layer includes a seed crystal, and a first undoped gallium nitride layer, a first highly doped gallium nitride layer, a second undoped gallium nitride layer, and a second highly doped gallium nitride layer stacked on the seed crystal in sequence.

Compared with the prior art, the embodiment of the utility model provides a pair of fold GaN single crystal substrate who establishes high doping layer inserts the high concentration impurity doping layer of gallium nitride crystal through periodicity, interval formula, makes the stress of non-doping gallium nitride within a layer obtain effective release, has finally effectively improved the gallium nitride crystal quality of gained.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a schematic structural view of a GaN single crystal substrate stacked with highly doped layers provided in embodiment 1 of the present invention;

FIG. 2 is a schematic view of the growth principle of a GaN single crystal according to the present invention.

Detailed Description

In view of the deficiencies in the prior art, the inventor of the present invention has made extensive studies and practices to provide the technical solution of the present invention. The technical solution, its implementation and principles, etc. will be further explained as follows.

Further, the plurality of undoped layers and the plurality of highly doped gallium nitride layers are alternately arranged in sequence.

Furthermore, the stacked high-doped layer GaN single crystal substrate comprises a plurality of high-doped gallium nitride layers and a plurality of second non-doped gallium nitride layers, and the plurality of high-doped gallium nitride layers and the plurality of second non-doped gallium nitride layers are periodically and alternately stacked on the first non-doped gallium nitride layer in sequence.

Further, the thickness of the first non-doped gallium nitride layer is 20-50 μm, the thickness of the highly doped gallium nitride layer is 20-50 μm, the thickness of the second non-doped gallium nitride layer is 300-400 μm, and the doping concentration of the highly doped gallium nitride layer is not less than 10 ≥ m¹⁹cm^-3The impurity doped by the high-doped gallium nitride layer includes but is not limited to C, H, O, Si, Mg, Al, Fe and other elements.

Furthermore, the stacked high-doped layer GaN single crystal substrate comprises a plurality of second non-doped gallium nitride layers and a plurality of second high-doped gallium nitride layers, and the plurality of second non-doped gallium nitride layers and the plurality of second high-doped gallium nitride layers are periodically and sequentially stacked on the first high-doped gallium nitride layer in an alternating manner.

Furthermore, the thickness of the first non-doped gallium nitride layer is 20-50 μm, the thickness of the first highly-doped gallium nitride layer is 20-50 μm, and the doping concentration of the first highly-doped gallium nitride layer is not less than 10¹⁹cm^-3The thickness of the second non-doped gallium nitride layer is 300-400 mu m, the thickness of the second highly-doped gallium nitride layer is 20-50 mu m, and the doping concentration of the second highly-doped gallium nitride layer is not less than 10¹⁹cm^-3。

Further, the impurities doped in the first highly doped gallium nitride layer and the second highly doped gallium nitride layer include, but are not limited to, C, H, O, Si, Mg, Al, Fe, and the like.

Further, the undoped gallium nitride layer and the highly doped gallium nitride layer are obtained by changing growth conditions during growth by a flux method, wherein the seed crystal comprises a GaN seed crystal.

In the following, the technical solution, the implementation process and the principle thereof will be further explained with reference to the drawings, and if not specifically stated, the manufacturing process and the materials used in the embodiments of the present invention can all be known to those skilled in the art.

Example 1

Referring to fig. 1, a GaN single crystal substrate with stacked highly doped layers includes a first undoped gallium nitride layer 100, a first highly doped gallium nitride layer 200, a second undoped gallium nitride layer 300 and a second highly doped gallium nitride layer 400 which are stacked in sequence along a designated direction and are periodically grown, wherein the number of growth cycles of the second undoped gallium nitride layer 300 and the second highly doped gallium nitride layer 400 is greater than or equal to 1.

Specifically, the thickness of the first undoped gallium nitride layer 100 is 20-50 μm, the thickness of the first highly-doped gallium nitride layer 200 is 20-50 μm, the thickness of the second undoped gallium nitride layer 300 is 300-400 μm, and the thickness of the second highly-doped gallium nitride layer 400 is 20-50 μm. .

Specifically, the thickness of the first non-doped gallium nitride layer is 20-50 μm, the thickness of the first highly-doped gallium nitride layer is 20-50 μm, and the doping concentration of the first highly-doped gallium nitride layer is not less than 10¹⁹cm^-3The thickness of the second non-doped gallium nitride layer is 300-400 mu m, the thickness of the second highly-doped gallium nitride layer is 20-50 mu m, and the doping concentration of the second highly-doped gallium nitride layer is not less than 10¹⁹cm^-3The impurities doped in the first highly doped gallium nitride layer and the second highly doped gallium nitride layer include, but are not limited to, C, H, O, Si, Mg, Al, Fe, and the like.

Specifically, the GaN single crystal substrate stacked with the high doping layer is formed by direct epitaxial growth using a flux method, and for example, a method for manufacturing a GaN single crystal substrate stacked with a high doping layer may include: using metal Ga and Na as raw materials, using GaN grown by HVPE (hydride vapor phase epitaxy) as a seed crystal, using a crucible as a growth container, and growing under the conditions of specified temperature and pressure to form the GaN single crystal substrate with the stacked highly doped layers; the method specifically comprises the following steps:

1) controlling the growth conditions, and growing a first non-doped gallium nitride layer 100 with the thickness of 20-50 mu m on the GaN seed crystal 500;

2) growing a first highly doped gallium nitride layer (doped impurity species including but not limited to C, H, O, Si, Mg, Al, Fe, etc.) 200 with a thickness of 20-50 μm on the first undoped gallium nitride layer 100 by changing the growth conditions;

3) ending the growth of the first highly doped gallium nitride layer 200, continuing to grow a second non-doped gallium nitride layer (which may be called as a gallium nitride crystal non-doped layer) 300 with the thickness of 300-400 μm on the first highly doped gallium nitride layer 200 by a flux method, and then inserting a second highly doped gallium nitride layer (the doped impurity species include but are not limited to C, H, O, Si, Mg, Al, Fe and other elements) 400 with the thickness of 20-50 μm on the second non-doped gallium nitride layer 300;

4) then the second non-doped gallium nitride layer 300/20-50 μm second highly doped gallium nitride layer 400 with the thickness of 300-400 μm is grown alternately and periodically until the required thickness is obtained.

Referring to FIG. 2, a non-destructive Raman test is used as a method for detecting internal stress during crystal growth, and E in bulk GaN in an unstressed state is known from the prior art₂(high) has a peak value of 568.0cm^-1[1,2]From this, we can calculate the stress magnitude in different gallium nitride crystal samples according to the formula [3]:σ＝Δω/4.2(cm^- ¹GPa^-1) Where σ is the stress value and Δ ω is E₂(high) shift value of peak; thus, the value of stress in the crystal can be considered to follow E₂(high) increase in peak value, and in this understanding, the present invention employs E for periodic doping of samples₂(high) Peak, E can be seen in the crystal after insertion of the highly doped layer₂The (high) peak is significantly reduced, demonstrating a significant reduction in stress within the crystal.

[1]Z.Zheng,Z.Chen,H.Wu,Y.Chen,S.Huang,B.Fan,Y.Xian,Z.Wu,G.Wang,H.Jiang,Effect of periodic Si-delta-doping on the evolution of yellow luminescence and stress in n-type GaN epilayers,Journal of Crystal Growth,387(2014)52-56。

[2]L.Pan,X.Dong,Z.Li,W.Luo,J.Ni,Influence of the AlN nucleation layer on the properties of AlGaN/GaN heterostructure on Si(111)substrates,Applied Surface Science,447(2018)512-517.

[3]L.Qi,Y.Xu,Z.Li,E.Zhao,S.Yang,B.Cao,J.Zhang,J.Wang,K.Xu,Stress analysis of transferable crack-free gallium nitride microrods grown on graphene/SiC substrate,Materials Letters,185(2016)315-318。

The embodiment of the utility model provides a pair of fold GaN single crystal substrate who establishes high doping layer inserts the high concentration impurity doping layer of gallium nitride crystal (first high doping gallium nitride layer and second high doping gallium nitride layer promptly) through periodicity, spaced type, makes the stress of non-doping gallium nitride within a layer obtain effective release, has finally effectively improved the gallium nitride crystal quality of gained.

It should be understood that the above-mentioned embodiments are merely illustrative of the technical concepts and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention, and therefore, the protection scope of the present invention should not be limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. The GaN single crystal substrate with the stacked high-doped layers is characterized by comprising a seed crystal, a first non-doped gallium nitride layer, a plurality of high-doped gallium nitride layers and a plurality of second non-doped gallium nitride layers, wherein the first non-doped gallium nitride layer, the plurality of high-doped gallium nitride layers and the plurality of second non-doped gallium nitride layers are sequentially stacked on the seed crystal in sequence, and the plurality of high-doped gallium nitride layers and the plurality of second non-doped gallium nitride layers are periodically and alternately stacked on the first non-doped gallium nitride layer.

2. The GaN single crystal substrate stacked with high doping layers as claimed in claim 1, wherein: the thickness of the first non-doped gallium nitride layer is 20-50 μm, the thickness of the highly doped gallium nitride layer is 20-50 μm, the thickness of the second non-doped gallium nitride layer is 300-400 μm, and the doping concentration of the highly doped gallium nitride layer is not less than 10 ≥¹⁹ cm^-3。

3. The GaN single-crystal substrate stacked with highly doped layers according to claim 1, comprising a seed crystal, and a first undoped gallium nitride layer, a first highly doped gallium nitride layer, a second undoped gallium nitride layer and a second highly doped gallium nitride layer stacked on the seed crystal in this order.

4. The stacked GaN single crystal substrate of claim 3, comprising a plurality of second undoped gallium nitride layers and a plurality of second highly doped gallium nitride layers, wherein the plurality of second undoped gallium nitride layers and the plurality of second highly doped gallium nitride layers are alternately stacked on the first highly doped gallium nitride layer in a periodic manner.

5. The GaN single-crystal substrate stacked with high-doped layers according to claim 3, wherein: the thickness of the first non-doped gallium nitride layer is 20-50 mu m, the thickness of the first highly-doped gallium nitride layer is 20-50 mu m, and the doping concentration of the first highly-doped gallium nitride layer is not less than 10¹⁹ cm^-3The thickness of the second non-doped gallium nitride layer is 300-400 mu m, the thickness of the second highly-doped gallium nitride layer is 20-50 mu m, and the doping concentration of the second highly-doped gallium nitride layer is not less than 10¹⁹cm^-3。

6. The GaN single crystal substrate stacked with high doping layers as claimed in claim 1, wherein: the non-doped gallium nitride layer and the high-doped gallium nitride layer are obtained by changing growth conditions in the growth process of a fluxing agent method, wherein the seed crystal comprises a GaN seed crystal.