An InGaN / GaN multi-quantum well blue laser cell epitaxial wafer and a preparation method thereof

Abstract

The invention discloses an InGaN / GaN multi-quantum well blue laser cell epitaxial wafer and a preparation method thereof, belonging to the technical field of blue laser cell epitaxial wafers. The epitaxial wafer comprises an Al2O3 substrate, an AlN nucleation layer is arranged on the top surface of the Al2O3 substrate, a GaN intrinsic layer is arranged on the top surface of the AlN nucleation layer, an n-GaN layer is arranged on the top surface of the GaN intrinsic layer, and an InGaN layer is arranged on the top surface of the n-GaN layer. 0.04 Ga 0.96 N / GaN superlattice layer, In 0.04 Ga 0.96 The top surface of the N / GaN superlattice layer is provided with a u-GaN layer, and the top surface of the u-GaN layer is provided with an In 0.26 Ga 0.74 N / GaN multi-quantum well layer, the present invention improves In 0.26 Ga 0.74 Al at the interface of N / GaN multi-quantum well layer 0.1 Ga 0.9 The height of the N barrier layer improves the crystallization quality of p-GaN, reduces the interface state concentration, reduces the non-radiative recombination centers of the p-GaN layer, and improves the performance of InGaN / GaN multi-quantum well blue laser cells.

Description

Technical Field

[0001] The present invention relates to the technical field of blue laser cell epitaxial wafers, and more specifically to an InGaN / GaN multi-quantum well blue laser cell epitaxial wafer and a preparation method thereof. Background Art

[0002] Among the third-generation semiconductors, the III-V semiconductor GaN is representative. The bandgap of GaN is wide, reaching 3.4eV. Its melting point is as high as 1700℃, and its ionization degree is about 0.43-0.5. Not only that, GaN also has high thermal conductivity, breakdown electric field and thermal conductivity. It also has the advantages of strong radiation resistance and high hardness, and has great application value in the fields of optoelectronics and microelectronics. At present, although many aspects of In-doped GaN have been studied, they focus on the growth of InGaN absorption layer and subsequent device performance. Including the use of InGan / GaN quantum dots, the optimization of the number of multi-quantum well periods, the use of different substrates, and the growth of different GaN crystal orientations. These methods reveal the relationship between the material quality, structural integrity and corresponding photovoltaic properties of the InGaN layer.

[0003] The existing blue laser cell structure has a low light conversion efficiency, which reduces the overall performance of the cell. In view of this, we propose an InGaN / GaN multi-quantum well blue laser cell epitaxial wafer and a preparation method thereof. Summary of the invention

[0004] The purpose of the present invention is to provide an InGaN / GaN multi-quantum well blue laser cell epitaxial wafer and a preparation method thereof to solve the problem raised in the above background technology: the existing blue laser cell structure has a low light conversion efficiency, which reduces the overall performance of the cell.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] An InGaN / GaN multi-quantum well blue laser cell epitaxial wafer, comprising an Al2O3 substrate, an AlN nucleation layer is arranged on the top surface of the Al2O3 substrate, a GaN intrinsic layer is arranged on the top surface of the AlN nucleation layer, an n-GaN layer is arranged on the top surface of the GaN intrinsic layer, and an InGaN layer is arranged on the top surface of the n-GaN layer. 0.04 Ga 0.96 N / GaN superlattice layer, the In 0.04 Ga 0.96 The top surface of the N / GaN superlattice layer is provided with a u-GaN layer, and the top surface of the u-GaN layer is provided with an In 0.26 Ga 0.74 N / GaN multi-quantum well layer, the In 0.26 Ga 0.74The top surface of the N / GaN multi-quantum well layer is provided with Al 0.1 Ga 0.9 N barrier layer, the Al 0.1 Ga 0.9 A p-GaN layer is disposed on the top surface of the N barrier layer.

[0007] Preferably, the Al 0.1 Ga 0.9 The thickness of the N barrier layer is 5 nm, the thickness of the u-GaN layer is 1.8 μm, the thickness of the AlN nucleation layer is 2 μm, and the thickness of the GaN intrinsic layer is 1400 nm.

[0008] Preferably, the doping concentration of heavily doped n-type GaN in the n-GaN layer is 1×10 19 cm -3 , thickness is 1.8μm; lightly doped n-type GaN doping concentration is 1×10 18 cm -3 , with a thickness of 200nm.

[0009] Preferably, the In 0.04 Ga 0.96 The number of N / GaN superlattice layer growth cycles is 3, and each In 0.04 Ga 0.96 The thickness of the N layer is 10nm, and the thickness of each GaN layer is 40nm.

[0010] Preferably, the In 0.17 Ga 0.83 The number of quantum well periods in the N / GaN quantum well layer is 12, and each In 0.17 Ga 0.83 The thickness of the N layer is 3nm, and the thickness of each GaN layer is 10nm.

[0011] Preferably, the doping concentration of lightly doped p-type GaN in the p-GaN layer is 1×10 20 cm -3 , thickness is 50nm; heavily doped p-type GaN doping concentration is 5×10 18 cm -3 , thickness is 350nm.

[0012] Preferably, a method for preparing an InGaN / GaN multi-quantum well blue laser cell epitaxial wafer comprises the following steps:

[0013] S1: growing an AlN nucleation layer on a substrate at low temperature;

[0014] S2: growing a GaN intrinsic layer on the AlN nucleation layer at low temperature;

[0015] S3: growing a heavily doped n-type GaN layer on the GaN intrinsic layer at high temperature, and then growing a lightly doped n-type GaN layer;

[0016] S4: Under medium temperature conditions, In is grown on the n-type GaN layer 0.04 Ga 0.96 N / GaN superlattice layer;

[0017] S5: growing a u-GaN layer at high temperature;

[0018] S6: Growth In 0.16 Ga 0.84 N / GaN quantum well layer;

[0019] S7: growing an AlGaN barrier layer at medium temperature;

[0020] S8: growing a lightly doped p-GaN layer:Mg layer at low temperature, and then growing a heavily doped p-type GaN:Mg layer to prepare the epitaxial wafer.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention further solves the problem of surface recombination near the contact and improves carrier collection by epitaxially extending a certain thickness of Al 0.1 Ga 0.9 N barrier layer further increases the In 0.26 Ga 0.74 Al at the interface of N / GaN multi-quantum well layer 0.1 Ga 0.9 The height of the N barrier layer improves the crystal quality of p-GaN, reduces the interface state concentration, reduces the non-radiative recombination center of the p-GaN layer, improves the collection of holes in the p-GaN layer, and improves the performance of InGaN / GaN multi-quantum well blue laser cells to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0024] Figure 2 Schematic diagram of the MQW structure of sample B;

[0025] Figure 3 Schematic diagram of the MQW structure of sample A;

[0026] Figure 4 is a schematic diagram of the rocking curve of the (002) plane;

[0027] Figure 5 Schematic diagram of the (102) surface rocking curve. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0029] Embodiment 1:

[0030] See also Figure 1-5 An InGaN / GaN multi-quantum well blue laser cell epitaxial wafer and a substrate, comprising an Al2O3 substrate, an AlN nucleation layer is disposed on the top surface of the Al2O3 substrate, a GaN intrinsic layer is disposed on the top surface of the AlN nucleation layer, an n-GaN layer is disposed on the top surface of the GaN intrinsic layer, and an InGaN layer is disposed on the top surface of the n-GaN layer. 0.04 Ga 0.96 N / GaN superlattice layer, In 0.04 Ga 0.96 The top surface of the N / GaN superlattice layer is provided with a u-GaN layer, and the top surface of the u-GaN layer is provided with an In 0.26 Ga 0.74 N / GaN multiple quantum well layer, In 0.26 Ga 0.74 The top surface of the N / GaN multi-quantum well layer is provided with Al 0.1 Ga 0.9 N barrier layer, Al 0.1 Ga 0.9 A p-GaN layer is disposed on the top surface of the N barrier layer.

[0031] Al 0.1 Ga 0.9 The thickness of the N barrier layer is 5 nm;

[0032] The thickness of the u-GaN layer is 1.8 μm, and the u-GaN layer as a buffer layer is used to adjust the strain between the superlattice layer and the quantum well layer, while reducing impurity scattering;

[0033] The thickness of the AlN nucleation layer is 2 μm;

[0034] The thickness of the GaN intrinsic layer is 1400nm.

[0035] The doping concentration of heavily doped n-type GaN in the n-GaN layer is 1×10 19 cm -3 , thickness is 1.8μm; lightly doped n-type GaN doping concentration is 1×10 18 cm -3 , with a thickness of 200nm.

[0036] In 0.04 Ga 0.96 The number of N / GaN superlattice layer growth cycles is 3, and each In 0.04 Ga0.96 The thickness of the N layer is 10 nm, and the thickness of each GaN layer is 40 nm. The InGaN / GaN superlattice layer structure refers to a superlattice structure that includes both InGaN layers and GaN layers. In this structure, the InGaN layer and the GaN layer are grown alternately and periodically. For example, a GaN layer is grown on an InGaN layer, and then another InGaN layer is grown on the GaN layer, and this is repeated periodically and alternately.

[0037] In 0.17 Ga 0.83 The number of quantum well periods in the N / GaN quantum well layer is 12, and each In 0.17 Ga 0.83 The thickness of the N layer is 3nm, and the thickness of each GaN layer is 10nm.

[0038] The doping concentration of lightly doped p-type GaN in the p-GaN layer is 1×10 20 cm -3 , thickness is 50nm; heavily doped p-type GaN doping concentration is 5×10 18 cm -3 , thickness is 350nm.

[0039] The present invention further solves the surface recombination near the contact and improves the carrier collection by epitaxially extending a certain thickness of Al 0.1 Ga 0.9 N barrier layer further increases the In 0.26 Ga 0.74 Al at the interface of N / GaN multi-quantum well layer 0.1 Ga 0.9 The height of the N barrier layer improves the crystal quality of p-GaN, reduces the interface state concentration, reduces the non-radiative recombination center of the p-GaN layer, improves the collection of holes in the p-GaN layer, and improves the performance of InGaN / GaN multi-quantum well blue laser cells to a certain extent.

[0040] A method for preparing an InGaN / GaN multi-quantum well blue laser cell epitaxial wafer comprises the following steps:

[0041] S1: Using MOCVD equipment, a 2μm thick AlN nucleation layer is grown on the substrate at low temperature;

[0042] S2: growing a 1400nm thick GaN intrinsic layer on the AlN nucleation layer at low temperature;

[0043] S3: At high temperature, a heavily doped n-type GaN layer 4 with a thickness of 1.8 μm is grown on the GaN intrinsic layer, and the doping concentration is 1×10 19 cm -3Then, a 200 nm thick lightly doped n-type GaN layer was grown with a doping concentration of 1 × 10 18 cm -3 ;

[0044] S4: Growing 3 cycles of In on the n-type GaN layer at medium temperature 0.04 Ga 0.96 N / GaN superlattice layer, each layer of In 0.04 Ga 0.96 The thickness of the N layer is 10nm, and the thickness of each GaN layer is 40nm;

[0045] S5: growing a u-GaN layer with a thickness of 1.8 μm at high temperature;

[0046] S6: Growth In 0.16 Ga 0.84 N / GaN quantum well layer, the number of quantum well periods is 12, each layer of In 0.16 Ga 0.84 The thickness of the N layer is 3nm, and the thickness of each GaN layer is 10nm;

[0047] S7: growing an AlGaN barrier layer with a thickness of 5 nm under medium temperature conditions;

[0048] S8: A lightly doped p-GaN layer with a thickness of 350 nm is grown at low temperature: the Mg layer has a doping concentration of 5×10 18 cm -3 Then, a heavily doped p-type GaN:Mg layer with a thickness of 40 nm and a doping concentration of 1×10 21 cm -3 , that is, the epitaxial wafer is prepared.

[0049] After sample A was prepared according to the above method, sample B was grown, wherein sample B did not have a process of growing an AlGaN barrier layer, and the rest of the process was consistent with the growth process of sample A.

[0050] The present invention not only has an InGaN / GaN superlattice structure, but also reduces the piezoelectric polarization intensity and ionized impurity scattering, and grows Al behind the InGaN / GaN multi-quantum well layer. 0.1 Ga 0.9 N barrier layer, to obtain a quantum well with higher crystal quality. Compared with traditional laser cells, the laser cells made with this structure have more carrier collection and less surface recombination, which improves the performance of InGaN / GaN multi-quantum well blue laser cells to a certain extent.

[0051] 1. The two samples have highly similar MQW structures, indicating that there is no negative effect caused by the addition of the AlGaN layer, such as Figure 2-3 shown.

[0052] 2. Rocking curves of (002) and (102) planes: Figure 4-5 shown.

[0053]

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. An InGaN / GaN multi-quantum well blue laser cell epitaxial wafer, characterized in that: The invention comprises an Al2O3 substrate, wherein an AlN nucleation layer is disposed on the top surface of the Al2O3 substrate, a GaN intrinsic layer is disposed on the top surface of the AlN nucleation layer, an n-GaN layer is disposed on the top surface of the GaN intrinsic layer, and an In 0.04 Ga 0.96 N / GaN superlattice layer, the In 0.04 Ga 0.96 The top surface of the N / GaN superlattice layer is provided with a u-GaN layer, and the top surface of the u-GaN layer is provided with an In 0.26 Ga 0.74 N / GaN multi-quantum well layer, the In 0.26 Ga 0.74 The top surface of the N / GaN multi-quantum well layer is provided with Al 0.1 Ga 0.9 N barrier layer, the Al 0.1 Ga 0.9 A p-GaN layer is disposed on the top surface of the N barrier layer; The Al 0.1 Ga 0.9 The thickness of the N barrier layer is 5 nm, the thickness of the u-GaN layer is 1.8 μm, the thickness of the AlN nucleation layer is 2 μm, and the thickness of the GaN intrinsic layer is 1400 nm; In 0.04 Ga 0.96 The number of N / GaN superlattice layer growth cycles is 3, and each In 0.04 Ga 0.96 The thickness of the N layer is 10nm, and the thickness of each GaN layer is 40nm; In 0.17 Ga 0.83 The number of quantum well periods in the N / GaN quantum well layer is 12, and each In 0.17 Ga 0.83 The thickness of the N layer is 3nm, and the thickness of each GaN layer is 10nm; The p-GaN layer has a lightly doped p-type GaN doping concentration of 1×10 20 cm -3 , thickness is 50nm; heavily doped p-type GaN doping concentration is 5×10 18 cm -3 , Thickness: 350nm; The method for preparing the InGaN / GaN multi-quantum well blue laser cell epitaxial wafer comprises the following steps: S1: growing an AlN nucleation layer on a substrate at a first temperature; S2: growing a GaN intrinsic layer on the AlN nucleation layer at a first temperature; S3: at a third temperature, growing a heavily doped n-type GaN layer on the GaN intrinsic layer, and then growing a lightly doped n-type GaN layer; S4: Under the second temperature condition, In is grown on the n-type GaN layer. 0.04 Ga 0.96 N / GaN superlattice layer; S5: growing a u-GaN layer at a third temperature; S6: Growth In 0.16 Ga 0.84 N / GaN quantum well layer; S7: growing an AlGaN barrier layer under a second temperature condition; S8: growing a lightly doped p-GaN layer:Mg layer at a first temperature, and then growing a heavily doped p-type GaN:Mg layer to prepare the epitaxial wafer; The third temperature is higher than the second temperature, and the second temperature is higher than the first temperature.

2. The InGaN / GaN multi-quantum well blue laser cell epitaxial wafer according to claim 1, characterized in that: The doping concentration of heavily doped n-type GaN in the n-GaN layer is 1×10 19 cm -3 , thickness is 1.8μm; lightly doped n-type GaN doping concentration is 1×10 18 cm -3 , thickness is 200nm.

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