Epitaxial layer structure of a pin type solar blind detector and method for producing same
By designing an asymmetric (β-Ga2O3)m / (Al2O3)n superlattice layer and a GaOx2N1-x2 interface layer, the crystal defect problem of β-Ga2O3 material during epitaxial growth was solved, realizing a high-quality PIN-type solar-blind detector epitaxial layer structure and improving device performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHANGSHU INSTITUTE OF TECHNOLOGY
- Filing Date
- 2026-03-24
- Publication Date
- 2026-06-16
AI Technical Summary
During the epitaxial growth of β-Ga2O3 materials, local stress can easily lead to crystal defects such as dislocations and vacancies, as well as the formation of twin structures, which can affect device performance. Furthermore, the lack of suitable low-cost large-size substrates can cause heat dissipation problems in the devices.
A high-quality N-type β-Ga2O3 epitaxial growth was achieved by employing an asymmetric (β-Ga2O3)m / (Al2O3)n superlattice layer, introducing controllable in-plane compressive stress through the Inx1Ga1-x1N/GaN superlattice layer, providing tensile stress compensation through the Al2O3 sublayer, and mitigating polarity abrupt changes by repeatedly bending and blocking dislocation extension through the superlattice interface, combined with the gradual change in chemical bond type of the GaOx2N1-x2 interface layer.
This improved the quality of the epitaxial layer, enhanced the detection performance of the device, solved the crystal defect problem of β-Ga2O3 material during epitaxial growth, and provided a high-quality epitaxial layer structure for a PIN-type solar-blind detector.
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Figure CN122227686A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor device technology, specifically a PIN-type solar-blind detector epitaxial layer structure and its fabrication method. Background Technology
[0002] Solar-blind photodetectors (SBPDs) are core devices in fields such as deep space exploration, missile early warning, and ozone monitoring. Compared to traditional technologies, gallium oxide (Ga2O3) is an emerging ultra-wide bandgap semiconductor material with a bandgap of up to 4.9 eV and an absorption cutoff wavelength of approximately 254 nm, perfectly falling within the solar-blind band. This makes it intrinsically unresponsive to visible light, thus occupying an important position in SBPD research.
[0003] As the only crystalline phase stable under normal pressure, monoclinic β-Ga₂O₃ exhibits an absorption coefficient >10 in the solar-blind band. 5 cm -1 β-Ga₂O₃ is one of the most ideal materials for preparing SBPDs. However, β-Ga₂O₃ still faces many technical challenges in epitaxial growth and device fabrication. First, due to the low symmetry and strong anisotropy of its monoclinic crystal system, β-Ga₂O₃ is susceptible to local stress during epitaxial growth, which can induce crystal defects such as stacking faults, dislocations, and oxygen vacancies, as well as the formation of twin structures. This not only leads to crystal quality degradation and limits device performance, but also forms strong scattering centers or compensation centers for charge carriers, making the already difficult P-type doping due to the strong principal energy level even more challenging. Therefore, current research faces the challenge of low hole concentration and mobility. Second, there is a lack of suitable substrates for the epitaxial growth of β-Ga₂O₃: although commercially available homogeneous substrates exist, they are not only expensive and limited in size, but also suffer from heat dissipation problems due to insufficient thermal conductivity. Summary of the Invention
[0004] To address the aforementioned shortcomings of existing technologies, the present invention aims to provide a PIN-type epitaxial layer structure for a solar-blind detector. This structure addresses the problem that β-Ga₂O₃, being a monoclinic crystal system, exhibits low symmetry and strong anisotropy, making it susceptible to localized stress during epitaxial growth. This stress induces crystal defects such as dislocations and vacancies, as well as twin structures. These defects, acting as strong scattering or compensation centers for charge carriers, can restrict device performance. Another objective of the present invention is to provide a method for fabricating this PIN-type epitaxial layer structure for a solar-blind detector.
[0005] The technical solution of this invention is as follows: A PIN-type solar-blind detector epitaxial layer structure, comprising a substrate, wherein GaN nucleation layers and In are sequentially stacked and grown on the substrate from bottom to top. x1 Ga 1-x1N / GaN superlattice layer, P-type GaN layer, GaO x2 N 1-x2 Interface layer, (β-Ga2O3)m / (Al2O3)n superlattice layer and N-type β-Ga2O3 layer; the (β-Ga2O3)m / (Al2O3)n superlattice layer is an asymmetric superlattice, m is the number of β-Ga2O3 sublayers in a single period, n is the number of Al2O3 sublayers in a single period, along the production direction of the (β-Ga2O3)m / (Al2O3)n superlattice layer, the quantitative relationship between m and n gradually changes from m < n to m > n.
[0006] Furthermore, 1 ≤ m ≤ 10, 1 ≤ n ≤ 10, and m and n change gradiently along the production direction of the (β-Ga2O3)m / (Al2O3)n superlattice layer.
[0007] Furthermore, the number of periods of the (β-Ga2O3)m / (Al2O3)n superlattice layer is 5 - 50, the thickness of a single-layer β-Ga2O3 sublayer is 1 - 3 nm, and the thickness of a single-layer Al2O3 is 1 - 2 nm.
[0008] Furthermore, the x1 Ga 1-x1 number of periods of the In x1 Ga 1-x1 N / GaN superlattice layer is 10 - 20, the thickness of In
[0009] Furthermore, the x2 N 1-x2 value of X2 in the GaO
[0010] Furthermore, the x2 N 1-x2 interface layer increases gradiently along the growth direction, and 0 ≤ X2 ≤ 0.5. The interface layer with gradually changing composition realizes the gradual change of the chemical bond type from Ga-N bond to Ga-O bond, alleviates the polarity mutation, and realizes the lattice constant transition.
[0011] Furthermore, the substrate is a single substrate of any one of sapphire, gallium nitride, aluminum nitride, gallium oxide, diamond, silicon carbide, and silicon, or a composite substrate composed of any combination of multiple substances.
[0012] A method for fabricating an epitaxial layer structure for a PIN-type solar-blind detector, using an MOCVD device for material growth, includes the following steps: pre-treating the substrate by baking; then sequentially growing a GaN nucleation layer on the substrate using triethylgallium as a Group III precursor and ammonia as a Group V precursor; and growing an In layer using triethylgallium and triethylindium as Group III precursors and ammonia as a Group V precursor. x1 Ga 1-x1 N / GaN superlattice layers were prepared by growing P-type GaN layers using trimethylgallium as a Group III precursor, ammonia as a Group V precursor, and magnesia as a dopant source. GaO layers were prepared by growing GaO layers using triethylgallium as a Group III precursor, ammonia as a Group V precursor, oxygen as an oxygen source, and simultaneous pulsed introduction of silane. x2 N 1-x2 The interface layer is prepared by growing a (β-Ga2O3)m / (Al2O3)n superlattice layer using triethylgallium and triethylaluminum as group III precursors and nitric oxide as oxygen source. The N-type β-Ga2O3 layer is prepared by growing a trimethylgallium as group III precursor, oxygen as oxygen source and silane as dopant source. Finally, the layers are annealed in situ and then naturally cooled.
[0013] Furthermore, the growth preparation of In x1 Ga 1-x1 The N / GaN superlattice layer is grown with GaN as the top layer; when growing the (β-Ga2O3)m / (Al2O3)n superlattice layer, the growth ends with the β-Ga2O3 sublayer as the top layer.
[0014] Furthermore, the growth preparation of GaO x2 N 1-x2 During the interfacial layer, the oxygen to ammonia flow ratio gradually increases over time.
[0015] The advantages of this invention compared to the prior art are:
[0016] This invention catalyzes the formation of a thin layer of gallium oxynitride (GaON) transition region on the surface of P-type GaN, and on this basis, epitaxially grows an asymmetric (β-Ga2O3)m / (Al2O3)n superlattice layer, ultimately achieving high-quality epitaxial growth of N-type β-Ga2O3.
[0017] In x1 Ga 1-x1The InGaN superlattice layer introduces controllable in-plane compressive stress by using the relatively large radius of In atoms to partially offset the tensile stress brought by the subsequent N-type β-Ga2O3. In the asymmetric (β-Ga2O3)m / (Al2O3)n superlattice layer, the Al2O3 sublayer provides tensile stress compensation, and the dislocations are repeatedly "bent" and "blocked" at the superlattice interface to make them annihilate with each other. Finally, a thick N-type β-Ga2O3 layer is grown on the strain-modulated superlattice, and the epitaxial quality is significantly improved. The high-quality epitaxial layer will greatly contribute to improving the overall detection performance of the device. Description of the Drawings
[0018] Figure 1 Schematic diagram of the epitaxial layer structure of the PIN-type solar-blind detector in the embodiment. Detailed Embodiment
[0019] The present invention will be further described below in conjunction with embodiments, but it is not intended to limit the present invention.
[0020] Please refer to Figure 1 As shown, the epitaxial layer structure of the PIN-type solar-blind detector in Embodiment 1 includes a sapphire substrate 1, on which a GaN nucleation layer 2 with a thickness of 3 nm, an In x1 Ga 1-x1 GaN superlattice layer 3, a P-type GaN layer with a thickness of 500 nm, a GaO[[ID=二十二]] x2 N 1-x2 interface layer, a (β-Ga2O3)m / (Al2O3)n superlattice layer, and an N-type β-Ga2O3 layer with a thickness of 500 nm are sequentially stacked.
[0021] Among them, the period number of the In x1 Ga 1-x1 GaN superlattice layer 3 is 10, X1 = 0.05, the thickness of In x1 Ga 1-x1 N in a single period is 1 nm, and the thickness of GaN in a single period is 1 nm. The X2 of the GaO x2 N 1-x2 interface layer is 0.1. The (β-Ga2O3)m / (Al2O3)n superlattice layer is an asymmetric superlattice with a period number of 5. m is the number of β-Ga2O3 sublayers in a single period, n is the number of Al2O3 sublayers in a single period, and the thicknesses of both the β-Ga2O3 sublayer and the Al2O3 sublayer are 1 nm. 1 ≤ m ≤ 10, 1 ≤ n ≤ 10, along the production direction of the (β-Ga2O3)m / (Al2O3)n superlattice layer, m and n change gradually, and the quantitative relationship between m and n changes from m < n to m > n. Specifically, in the first 1 / 2 period, m < n, and in the latter 1 / 2 period, m > n.
[0022] The fabrication method of the epitaxial layer structure of the PIN-type solar-blind detector in this embodiment uses an MOCVD device for material growth and specifically includes the following steps:
[0023] (1) Pretreatment of substrate 1: First, set the vacuum degree to 8000 Pa and the substrate heating temperature to 1000℃, and bake in a hydrogen (H2) atmosphere for 3 to 8 minutes; then, set the substrate temperature to 900℃, and introduce a mixture of ammonia (NH3) and hydrogen (H2) gas with a gas flow ratio of 1:3, and pretreat under these conditions for 1 to 2 minutes.
[0024] (2) A GaN nucleation layer 2 is grown on substrate 1, with a flow rate of 10 sccm for the group III precursor: triethylgallium (TEGa); a flow rate of 300 sccm for the group V precursor: ammonia (NH3); a flow rate of 500 sccm for the carrier gas: nitrogen (N2); a growth temperature of 680℃; and a growth pressure of 5000 Pa.
[0025] (3) In growth on GaN nucleation layer 2 x1 Ga 1-x1 The N / GaN superlattice layer 3 has the following parameters: Group III precursors: triethylgallium (TEGa) with a flow rate of 10 sccm and triethylin (TEIn) with a flow rate of 10 sccm; Group V precursor: ammonia (NH3) with a flow rate of 1000 sccm; carrier gas: nitrogen (N2) with a flow rate of 500 sccm; growth temperature: 850℃; growth pressure: 5000 Pa; during growth, the TEIn source is pulsed to react with TEGa and NH3, and the pulse supply time of the TEIn source in a single cycle is 1 second; the entire In... x1 Ga 1-x1 The growth of the N / GaN superlattice layer 3 ends with the GaN layer as the top layer.
[0026] (4) In In x1 Ga 1-x1 A P-type GaN layer 4 is grown on an N / GaN superlattice layer 3. The flow rate of the group III precursor, trimethylgallium (TMGa), is 10 sccm; the flow rate of the group V precursor, ammonia (NH3), is 1000 sccm; the flow rate of the dopant source, magnesia-dicenocene (Cp2Mg), is 40 sccm; the flow rate of the carrier gas, nitrogen (N2), is 500 sccm; the growth temperature is 950℃; and the growth pressure is 5000 Pa.
[0027] (5) Growing GaO on P-type GaN layer 4 x2 N 1-x2Interface layer 5: Group III precursor: triethylgallium (TEGa) with a flow rate of 10 sccm; Group V precursor: ammonia (NH3) with a flow rate of 500 sccm; oxygen source: high-purity oxygen (O2) with a flow rate of 10 sccm; the flow ratio of high-purity oxygen (O2) to ammonia (NH3) (O2 / NH3) increases linearly from 0.01 to 0.5, with a linear gradient step size of 0.05; growth time: 60 seconds; carrier gas: nitrogen (N2) with a flow rate of 500 sccm; growth temperature: 800℃; growth pressure: 5000 Pa; during the growth process, silane (SiH4) is simultaneously pulsed in at a flow rate of 10 sccm, with a pulse period of 3 seconds.
[0028] (6) In GaO x2 N 1-x2 A (β-Ga2O3)m / (Al2O3)n superlattice layer 6 was grown on interface layer 5. The flow rate of triethylgallium (TEGa) was 10 sccm and the flow rate of triethylaluminum (TEAl) was 50 sccm. The oxygen source was nitrogen oxide (N2O) with a flow rate of 200 sccm. The carrier gas was nitrogen (N2) with a flow rate of 500 sccm. The growth temperature was 600–950 ℃ and the growth pressure was 5000 Pa. Within a single cycle, the growth of each layer in the asymmetric superlattice is achieved by controlling the growth time. Specifically: in the first cycle, β-Ga2O3 grows for 2 seconds and Al2O3 grows for 8 seconds; in the third cycle, β-Ga2O3 grows for 5 seconds and Al2O3 grows for 5 seconds; in the fifth cycle, β-Ga2O3 grows for 9 seconds and Al2O3 grows for 1 second, and so on, forming a gradient-changing asymmetric superlattice. The growth of the (β-Ga2O3)m / (Al2O3)n superlattice layer 6 ends with the β-Ga2O3 sublayer as the top layer.
[0029] (7) An N-type β-Ga2O3 layer 7 was grown on the (β-Ga2O3)m / (Al2O3)n superlattice layer 6. The flow rate of the group III precursor, trimethylgallium (TMGa), was 10 sccm; the flow rate of the oxygen source, high-purity oxygen (O2), was 10 sccm; the flow rate of the dopant source, silane (SiH4), was 10 sccm; the flow rate of the carrier gas, nitrogen (N2), was 500 sccm; the growth temperature was 700℃; and the growth pressure was 5000Pa.
[0030] (8) In-situ annealing process, a mixture of oxygen (O2) and nitrogen (N2) gas is introduced, and the gas flow ratio is: O2:N2=1:2; annealing temperature: 800℃, pressure: 8000 Pa, annealing time: 60 seconds.
[0031] (9) After completion of growth, evacuate the exhaust gas, and after natural cooling in-situ, take out the epitaxial wafer.
[0032] The PIN-type solar-blind detector epitaxial layer structure of Example 2 includes a sapphire substrate 1, on which a GaN nucleation layer 2 with a thickness of 6 nm, an In x1 Ga 1-x1 N / GaN superlattice layer 3, a P-type GaN layer with a thickness of 1000 nm, a GaO x2 N 1-x2 interface layer, a (β-Ga2O3)m / (Al2O3)n superlattice layer, and an N-type β-Ga2O3 layer with a thickness of 1000 nm are sequentially stacked.
[0033] Among them, the period number of the In x1 Ga 1-x1 N / GaN superlattice layer 3 is 15, X1 = 0.07, the thickness of In x1 Ga 1-x1 N in a single period is 2 nm, and the thickness of GaN in a single period is 4 nm. GaO x2 N 1-x2 The X2 of the interface layer is 0.3. The (β-Ga2O3)m / (Al2O3)n superlattice layer is an asymmetric superlattice with a period number of 15. m is the number of β-Ga2O3 sub-layers in a single period, n is the number of Al2O3 sub-layers in a single period, the thickness of the β-Ga2O3 sub-layer is 2 nm, and the thickness of each Al2O3 sub-layer is 1.5 nm. 1 ≤ m ≤ 10, 1 ≤ n ≤ 10, along the production direction of the (β-Ga2O3)m / (Al2O3)n superlattice layer, m and n change gradually, and the quantitative relationship between m and n changes from m < n to m > n. Specifically, in the first 1 / 2 period, m < n, and in the latter 1 / 2 period, m > n.
[0034] The preparation method of the PIN-type solar-blind detector epitaxial layer structure of this embodiment uses an MOCVD device for material growth, which specifically includes the following steps:
[0035] (1) Pretreatment of the substrate 1: First, set the vacuum degree to 9000 Pa, set the substrate heating temperature to 1050 °C, and perform baking treatment for 5 minutes in a hydrogen (H2) atmosphere; then, set the substrate temperature to 1000 °C, and introduce a mixed gas of ammonia (NH3) and hydrogen (H2), and the gas flow ratio is: 1:4, and perform pretreatment for 1.5 minutes under this condition.
[0036] (2) A GaN nucleation layer 2 is grown on substrate 1, with a flow rate of 50 sccm for the group III precursor: triethylgallium (TEGa); a flow rate of 500 sccm for the group V precursor: ammonia (NH3); a flow rate of 1000 sccm for the carrier gas: nitrogen (N2); a growth temperature of 800 ℃; and a growth pressure of 7000 Pa.
[0037] (3) In growth on GaN nucleation layer 2 x1 Ga 1-x1 The N / GaN superlattice layer 3 has the following parameters: Group III precursors: triethylgallium (TEGa) with a flow rate of 30 sccm and triethylin (TEIn) with a flow rate of 30 sccm; Group V precursor: ammonia (NH3) with a flow rate of 1500 sccm; carrier gas: nitrogen (N2) with a flow rate of 1000 sccm; growth temperature: 900 ℃; growth pressure: 7000 Pa; during growth, the TEIn source is pulsed to react with TEGa and NH3, and the pulse supply time of the TEIn source in a single cycle is 2 seconds; the entire In... x1 Ga 1-x1 The growth of the N / GaN superlattice layer 3 ends with the GaN layer as the top layer.
[0038] (4) In In x1 Ga 1-x1 A P-type GaN layer 4 is grown on an N / GaN superlattice layer 3. The flow rate of the group III precursor, trimethylgallium (TMGa), is 40 sccm; the flow rate of the group V precursor, ammonia (NH3), is 1500 sccm; the flow rate of the dopant source, magnesia-dicenocene (Cp2Mg), is 80 sccm; the flow rate of the carrier gas, nitrogen (N2), is 1500 sccm; the growth temperature is 1000 ℃; and the growth pressure is 8000 Pa.
[0039] (5) Growing GaO on P-type GaN layer 4 x2 N 1-x2 Interface layer 5: Group III precursor: triethylgallium (TEGa) flow rate 30 sccm; Group V precursor: ammonia (NH3) flow rate 800 sccm; oxygen source: high-purity oxygen (O2) flow rate 800 sccm; the flow rate ratio of high-purity oxygen (O2) to ammonia (NH3) (O2 / NH3) linearly increases from 0.01 to 0.5, with a linear gradient step size of 0.07; growth time 120 seconds; carrier gas: nitrogen (N2) flow rate 1000 sccm; growth temperature 950 ℃; growth pressure: 8500 Pa; during the growth process, silane (SiH4) is simultaneously pulsed in at a flow rate of 20 sccm, with a pulse period of 7 seconds.
[0040] (6) In GaO x2 N 1-x2 A (β-Ga2O3)m / (Al2O3)n superlattice layer 6 was grown on interface layer 5. The flow rate of the group III precursors was 80 sccm for triethylgallium (TEGa) and 100 sccm for triethylaluminum (TEAl). The oxygen source was 1000 sccm for nitrogen oxide (N2O) and 1500 sccm for nitrogen (N2). The growth temperature was 870 ℃ and the growth pressure was 7500 Pa. Within a single cycle, the growth of each layer in the asymmetric superlattice is achieved by controlling the growth time. Specifically: in the first cycle, β-Ga2O3 grows for 0.5 seconds and Al2O3 grows for 7.5 seconds; in the fifth cycle, β-Ga2O3 grows for 2.5 seconds and Al2O3 grows for 5 seconds; in the tenth cycle, β-Ga2O3 grows for 5 seconds and Al2O3 grows for 2.5 seconds; in the fifteenth cycle, β-Ga2O3 grows for 7.5 seconds and Al2O3 grows for 0.5 seconds, and so on, forming a gradient-changing asymmetric superlattice. The growth of the (β-Ga2O3)m / (Al2O3)n superlattice layer 6 ends with the β-Ga2O3 sublayer as the top layer.
[0041] (7) An N-type β-Ga2O3 layer 7 was grown on the (β-Ga2O3)m / (Al2O3)n superlattice layer 6. The flow rate of the group III precursor, trimethylgallium (TMGa), was 100 sccm; the flow rate of the oxygen source, high-purity oxygen (O2), was 850 sccm; the flow rate of the dopant source, silane (SiH4), was 40 sccm; the flow rate of the carrier gas, nitrogen (N2), was 1200 sccm; the growth temperature was 850 ℃; and the growth pressure was 8500 Pa.
[0042] (8) In-situ annealing process, a mixture of oxygen (O2) and nitrogen (N2) gas is introduced, and the gas flow ratio is: O2:N2=1:3; annealing temperature: 875 ℃, pressure: 10000 Pa, annealing time: 90 seconds.
[0043] (9) After growth is complete, exhaust the exhaust gas, allow it to cool naturally in situ, and then remove the epitaxial wafer.
[0044] The epitaxial layer structure of the PIN-type solar-blind detector in Example 3 includes a sapphire substrate 1, on which a GaN nucleation layer 2 with a thickness of 10 nm and an In layer 3 are sequentially stacked and grown. x1 Ga 1-x1 3. N / GaN superlattice layer, 2000 nm thick P-type GaN layer, 30 nm thick GaO x2 N 1-x2An interface layer, a (β-Ga2O3)m / (Al2O3)n superlattice layer, and an N-type β-Ga2O3 layer with a thickness of 2000 nm.
[0045] Among them, In x1 Ga 1-x1 The number of periods of the In x1 Ga 1-x1 N / GaN superlattice layer 3 is 20, X1 = 0.1, and the thickness of In x2 N within a single period is 3 nm, and the thickness of GaN within a single period is 7 nm. GaO x2 N 1-x2 X2 of the interface layer is 0.5. The (β-Ga2O3)m / (Al2O3)n superlattice layer is an asymmetric superlattice with 50 periods. m is the number of β-Ga2O3 sub-layers within a single period, n is the number of Al2O3 sub-layers within a single period. The thickness of the β-Ga2O3 sub-layer is 3 nm, and the thickness of each Al2O3 sub-layer is 2 nm. 1 ≤ m ≤ 10, 1 ≤ n ≤ 10. Along the production direction of the (β-Ga2O3)m / (Al2O3)n superlattice layer, m and n change gradually in a gradient manner, and the quantitative relationship between m and n changes from m < n to m > n. Specifically, within the first 1 / 2 period, m < n, and within the latter 1 / 2 period, m > n.
[0046] The preparation method of the PIN-type solar-blind detector epitaxial layer structure in this embodiment uses an MOCVD device for material growth, and specifically includes the following steps:
[0047] (1) Pretreatment of substrate 1: First, set the vacuum degree to 11000 Pa, set the substrate heating temperature to 1200 °C, and perform baking treatment for 3 - 8 minutes in a hydrogen (H2) atmosphere; then, set the substrate temperature to 1100 °C, and introduce a mixed gas of ammonia (NH3) and hydrogen (H2), and the gas flow ratio is: 1:5, and perform pretreatment for 2 minutes under this condition.
[0048] (2) Grow a GaN nucleation layer 2 on substrate 1. The flow rate of the group III precursor: triethylgallium (TEGa) is 150 sccm; the flow rate of the group V precursor: ammonia (NH3) is 2000 sccm; the carrier gas: the flow rate of nitrogen (N2) is 2800 sccm; the growth temperature is 870 °C; the growth pressure is: 10000 Pa.
[0049] (3) Grow In x1 Ga 1-x1The N / GaN superlattice layer 3 has the following parameters: Group III precursors: triethylgallium (TEGa) with a flow rate of 60 sccm and triethylin (TEIn) with a flow rate of 60 sccm; Group V precursor: ammonia (NH3) with a flow rate of 2000 sccm; carrier gas: nitrogen (N2) with a flow rate of 3000 sccm; growth temperature: 1000 ℃; growth pressure: 10000 Pa; during growth, the TEIn source is pulsed to react with TEGa and NH3, and the pulse supply time of the TEIn source in a single cycle is 3 seconds; the entire In... x1 Ga 1-x1 The growth of the N / GaN superlattice layer 3 ends with the GaN layer as the top layer.
[0050] (4) In In x1 Ga 1-x1 A P-type GaN layer 4 is grown on an N / GaN superlattice layer 3. The flow rate of the group III precursor, trimethylgallium (TMGa), is 80 sccm; the flow rate of the group V precursor, ammonia (NH3), is 2000 sccm; the flow rate of the dopant source, magnesia-dicenocene (Cp2Mg), is 200 sccm; the flow rate of the carrier gas, nitrogen (N2), is 3000 sccm; the growth temperature is 1050 ℃; and the growth pressure is 10000 Pa.
[0051] (5) Growing GaO on P-type GaN layer 4 x2 N 1-x2 Interface layer 5: Group III precursor: triethylgallium (TEGa) flow rate 50 sccm; Group V precursor: ammonia (NH3) flow rate 1000 sccm; oxygen source: high-purity oxygen (O2) flow rate 1500 sccm; the flow rate ratio of high-purity oxygen (O2) to ammonia (NH3) (O2 / NH3) linearly increases from 0.01 to 0.5, with a linear gradient step size of 0.1; growth time 180 seconds; carrier gas: nitrogen (N2) flow rate 1500 sccm; growth temperature 1050 ℃; growth pressure: 10000 Pa; during the growth process, silane (SiH4) is simultaneously pulsed in at a flow rate of 30 sccm, with a pulse period of 10 seconds.
[0052] (6) In GaO x2 N 1-x2A (β-Ga2O3)m / (Al2O3)n superlattice layer 6 was grown on interface layer 5. The flow rate of triethylgallium (TEGa) was 200 sccm and the flow rate of triethylaluminum (TEAl) was 180 sccm. The oxygen source was nitrogen oxide (N2O) with a flow rate of 2500 sccm. The carrier gas was nitrogen (N2) with a flow rate of 3000 sccm. The growth temperature was 950 ℃ and the growth pressure was 10000 Pa. Within a single cycle, the growth of each layer in the asymmetric superlattice is achieved by controlling the growth time, specifically: Cycle 1: β-Ga2O3 grows for 0.2 seconds, Al2O3 grows for 10 seconds; Cycle 10: β-Ga2O3 grows for 2 seconds, Al2O3 grows for 8 seconds; Cycle 20: β-Ga2O3 grows for 4 seconds, Al2O3 grows for 6 seconds; Cycle 30: β-Ga2O3 grows for 4 seconds, Al2O3 grows for 5 seconds; Cycle 40: β-Ga2O3 grows for 8 seconds, Al2O3 grows for 2 seconds; Cycle 50: β-Ga2O3 grows for 10 seconds, Al2O3 grows for 0.2 seconds, and so on, forming a gradient-changing asymmetric superlattice, and the growth of the (β-Ga2O3)m / (Al2O3)n superlattice layer 6 ends with the β-Ga2O3 sublayer as the top layer.
[0053] (7) An N-type β-Ga2O3 layer 7 was grown on the (β-Ga2O3)m / (Al2O3)n superlattice layer 6. The flow rate of the group III precursor, trimethylgallium (TMGa), was 250 sccm; the flow rate of the oxygen source, high-purity oxygen (O2), was 1500 sccm; the flow rate of the dopant source, silane (SiH4), was 70 sccm; the flow rate of the carrier gas, nitrogen (N2), was 2000 sccm; the growth temperature was 1000 ℃; and the growth pressure was 10000 Pa.
[0054] (8) In-situ annealing process, a mixture of oxygen (O2) and nitrogen (N2) gas is introduced, and the gas flow ratio is: O2:N2=1:4; annealing temperature: 950 ℃, pressure: 15000 Pa, annealing time: 180 seconds.
[0055] (9) After growth is complete, exhaust the exhaust gas, allow it to cool naturally in situ, and then remove the epitaxial wafer.
[0056] Performance tests were conducted on the above embodiments and existing detector epitaxial mechanisms, and the results are shown in the table below.
[0057]
[0058] FWHM@(-201) represents the full width at half maximum (FWHM). The existing structure consists of an undoped GaN layer, a P-type GaN layer, and an N-type β-Ga2O3 layer sequentially on a sapphire substrate.
[0059] Finally, it should be noted that sapphire is used as the substrate in all the foregoing embodiments. In other embodiments of the present invention, any one of gallium nitride, aluminum nitride, gallium oxide, diamond, silicon carbide and silicon can be used as the substrate, or a composite substrate composed of any combination of sapphire, gallium nitride, aluminum nitride, gallium oxide, diamond, silicon carbide and silicon can be used.
Claims
1. A PIN-type solar-blind detector epitaxial layer structure, comprising a substrate, characterized in that, On the substrate, a GaN nucleation layer, In x1 Ga 1-x1 N / GaN superlattice layer, p-type GaN layer, GaO x2 N 1-x2 interface layer, (β-Ga2O3)m / (Al2O3)n superlattice layer, and n-type β-Ga2O3 layer are sequentially grown from bottom to top; the (β-Ga2O3)m / (Al2O3)n superlattice layer is an asymmetric superlattice, m is the number of β-Ga2O3 sublayers in a single period, n is the number of Al2O3 sublayers in a single period, and along the production direction of the (β-Ga2O3)m / (Al2O3)n superlattice layer, the quantitative relationship between m and n gradually changes from m < n to m > n.
2. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 1, characterized in that, 1≤m≤10, 1≤n≤10, and m and n vary in gradient along the production direction of the (β-Ga2O3)m / (Al2O3)n superlattice layer.
3. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 1 or 2, characterized in that, The (β-Ga2O3)m / (Al2O3)n superlattice layer has a period number of 5 to 50, the thickness of a single β-Ga2O3 sublayer is 1 to 3 nm, and the thickness of a single Al2O3 layer is 1 to 2 nm.
4. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 1, characterized in that, The In x1 Ga 1-x1 The number of periods in the N / GaN superlattice layer is 10–20, and the In content within a single period is... x1 Ga 1-x1 The thickness of N is 1–3 nm, and the thickness of GaN in a single period is 1–7 nm.
5. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 1, characterized in that, The GaO x2 N 1-x2 In the interface layer, the X2 value increases gradually along the growth direction, and 0 ≤ X2 ≤ 0.
5.
6. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 1, characterized in that, The GaO x2 N 1-x2 The thickness of the interface layer is 5–30 nm, the thickness of the GaN nucleation layer is 3–10 nm, and the thickness of the P-type GaN layer is 500–2000 nm.
7. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 1, characterized in that, The substrate is a single substrate of any one of the following materials: sapphire, gallium nitride, aluminum nitride, gallium oxide, diamond, silicon carbide, and silicon, or a composite substrate of any combination of multiple materials.
8. A method for fabricating a PIN-type solar-blind detector epitaxial layer structure as described in any one of claims 1 to 7, wherein material growth is performed using an MOCVD device, characterized in that... The substrate is pretreated by baking, and then a GaN nucleation layer is grown on the substrate sequentially using triethylgallium as a Group III precursor and ammonia as a Group V precursor. An In layer is then grown using triethylgallium and triethylindium as Group III precursors and ammonia as a Group V precursor. x1 Ga 1-x1 N / GaN superlattice layers were prepared by growing P-type GaN layers using trimethylgallium as a Group III precursor, ammonia as a Group V precursor, and magnesia as a dopant source. GaO layers were prepared by growing GaO layers using triethylgallium as a Group III precursor, ammonia as a Group V precursor, oxygen as an oxygen source, and simultaneous pulsed introduction of silane. x2 N 1-x2 The interface layer is prepared by growing a (β-Ga2O3)m / (Al2O3)n superlattice layer using triethylgallium and triethylaluminum as group III precursors and nitric oxide as oxygen source. The N-type β-Ga2O3 layer is prepared by growing a trimethylgallium as group III precursor, oxygen as oxygen source and silane as dopant source. Finally, the layers are annealed in situ and then naturally cooled.
9. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 8, characterized in that, The growth preparation of In x1 Ga 1-x1 The N / GaN superlattice layer is grown with GaN as the top layer; when growing the (β-Ga2O3)m / (Al2O3)n superlattice layer, the growth ends with the β-Ga2O3 sublayer as the top layer.
10. The method for fabricating the epitaxial layer structure of the PIN-type solar-blind detector according to claim 8, characterized in that, The growth preparation of GaO x2 N 1-x2 During the interfacial layer, the oxygen to ammonia flow ratio gradually increases over time.