InGaAs-P Geiger avalanche diode and preparation method thereof

Abstract

The invention discloses an indium gallium arsenic phosphorus Geiger avalanche diode, which comprises an indium phosphide substrate (1), and an n + type indium phosphorus buffer layer (2), an unintentional doped indium gallium arsenic phosphorus absorption layer (3), a gradient doped indium gallium arsenic phosphorus transition layer (4), an n + type indium phosphorus charge layer (5) and an unintentional doped indium phosphorus multiplication layer (6) which are sequentially extended on the indium phosphide substrate (1), a circular p + type doped region (7) and an annular p + type protection ring region (8) are formed on the surface of the unintentional doped indium phosphorus multiplication layer (6) by adopting a selective region doping technology and are concentric; a concentric annular isolation groove (9) is prepared outside the annular p + type protection ring area (8); and preparing a front electrode (10) and a back electrode (11) to form the planar / mesa composite Geiger avalanche diode. According to the invention, the photon detection efficiency of the device is improved, the working temperature of the device is improved, the barrier effect is eliminated, and ultra-high-sensitivity and ultra-fast-response photoelectric detection is realized for a single photon signal with the wavelength of 1.06 microns.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor optoelectronic devices and relates to an InGaAsP Geiger avalanche diode and a preparation method thereof. Background Art

[0002] Single-photon detection technology can realize high-precision detection of extremely weak photon signals, and can obtain a variety of information contained in the photon signal, such as flight time, photon intensity, spectral characteristics, etc. It has a wide range of applications in laser ranging, photon counting, quantum information, spectral analysis and other fields, and is one of the important photoelectric detection methods for quantitative and qualitative analysis. It usually includes photoconductors, photovoltaics and other photoelectric devices that use the internal photoelectric effect, as well as photomultiplier tubes, photocathodes, microchannel plates and other photoelectric devices that use the external photoelectric effect. Among them, photovoltaic semiconductor photodetectors based on Geiger avalanche diodes have become an important research direction due to their excellent performance and simple structure.

[0003] The short-wave infrared band has good atmospheric penetration characteristics and has relatively special target characteristic spectral lines, and is one of the important bands of single-photon detection technology. Generally, InGaAs Geiger avalanche photodiodes developed based on III-V materials are selected as single-photon detectors in the short-wave infrared band. The spectral response range covers 1.0μm to 1.7μm, and the spectral response peaks are at 1.31μm and 1.55μm. However, InGaAs Geiger avalanche photodiodes have low light absorption efficiency for 1.06μm wavelengths, which are more mature in technology and have higher emission power in lasers. Therefore, effectively improving the light absorption efficiency of Geiger avalanche photodiodes at 1.06μm wavelengths will significantly improve the device's photon detection efficiency.

[0004] The light absorption efficiency of the InGaAs Geiger avalanche photodiode at a wavelength of 1.06μm mainly depends on the absorption coefficient, which is a characteristic of the InGaAs absorption layer material itself and is related to the composition of the InGaAs ternary compound. Generally speaking, the composition of the InGaAs ternary compound that achieves a high lattice match with the InP substrate is difficult to adjust on demand. Therefore, it has become a new technical approach to use InGaAs-P quaternary compounds as absorption layer materials to replace InGaAs and to achieve a higher absorption coefficient at a wavelength of 1.06μm by adjusting the composition of the InGaAs-P quaternary compound. At the same time, in order to design and prepare InGaAs-P Geiger avalanche diodes with excellent performance, the InGaAs-P absorption layer material needs to achieve high-quality heteroepitaxial lattice matching with the InP multiplication layer material, and a transition layer needs to be designed to reduce the charge barrier effect caused by the inconsistent bandgap width between the two. Summary of the invention

[0005] (I) Purpose of the invention

[0006] The purpose of the present invention is to propose an InGaAsP Geiger avalanche diode and a preparation method thereof, so as to solve the problem of low response and slow response of the current InGaAs Geiger avalanche diode at a wavelength of 1.06μm, and to improve the device's photon detection efficiency, increase the device's operating temperature, eliminate the barrier effect, and realize ultra-high sensitivity and ultra-fast response photoelectric detection for single-photon signals with a wavelength of 1.06μm by means of reasonable adjustment of material components, increase of material bandgap width, gradient doping transition, etc.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides an InGaAsP Geiger avalanche diode, which uses heteroepitaxial technology such as MBE or MOCVD to sequentially epitaxially grow n + type indium phosphide buffer layer 2, unintentionally doped indium gallium arsenic phosphide absorption layer 3, gradient doped indium gallium arsenic phosphide transition layer 4, n + type indium phosphorus charge layer 5, unintentionally doped indium phosphorus multiplication layer 6; using dielectric film deposition, photolithography, and high-temperature diffusion processes, a circular p-type indium phosphorus charge layer 5 is formed on the surface of the unintentionally doped indium phosphorus multiplication layer 6 by selective doping technology + Type doping region 7, annular p + Type guard ring area 8, the two are concentric; passivation, photolithography, etching process, in the ring p + A concentric annular isolation groove 9 is prepared outside the type guard ring area 8; a front electrode 10 and a back electrode 11 are prepared by using metal film deposition, photolithography and etching processes to form a planar / table composite Geiger avalanche diode.

[0009] The impurity doping type of the gradient doped InGaAsP transition layer 4 is n-type, and the impurity doping concentration is from the gradient doped InGaAs transition layer 4 to n-type. + 2.0×10 at the interface of type indium phosphide charge layer 5 17 cm -3 The thickness of the interface between the gradient doped InGaAs transition layer 4 and the unintentionally doped InGaAsP absorption layer 3 is 1.0×10 17 cm -3 The thickness of the gradient-doped InGaAs transition layer 4 is 0.1-0.2 μm.

[0010] The composition of the unintentionally doped InGaAsP absorption layer 3 can be adjusted according to the wavelength of the laser to be measured. For example, if the laser wavelength is 1.06 μm, the composition of the corresponding InGaAsP absorption layer is In 0.85 GaAs 0.33 P.

[0011] Highly uniformly doped InP as n + The type indium phosphorus charge layer 5 has an impurity doping type of n type and an impurity doping concentration of 1.5 to 2.0×10 17 cm-3 , the charge layer thickness is 0.1~0.2μm.

[0012] The present invention also provides a method for preparing an InGaAsP Geiger avalanche diode, comprising the following steps:

[0013] In the first step, MOCVD deposition equipment is used on the indium phosphide substrate 1 to sequentially epitaxially grow the thickness to 0.5 μm and the doping concentration to 1E18 cm -3 n+ type indium phosphorus buffer layer 2, composition is In0.85GaAs0.33P, thickness is 2μm, unintentionally doped indium gallium arsenic phosphorus absorption layer 3, thickness is 0.1μm, doping concentration is 1.0-2.0E17cm -3 Gradient doped InGaAsP transition layer 4, thickness 0.1μm, doping concentration 2E17cm -3 n+ type indium phosphide charge layer 5, non-intentionally doped indium phosphide multiplication layer 6 with a thickness of 3.5 μm, see attached Figure 1 ; The impurity doping type of the gradient doped InGaAsP transition layer 4 is n-type, and the impurity doping concentration is from 2.0×10 17 cm -3 The thickness of the interface between the gradient doped InGaAs transition layer 4 and the unintentionally doped InGaAsP absorption layer 3 is 1.0×10 17 cm -3 The thickness of the gradient-doped InGaAs transition layer 4 is 0.1 μm.

[0014] In the second step, dielectric film deposition, photolithography, high temperature diffusion and other processes are used to form a circular p+ type doped region 7 with a diameter of 15 μm and an annular p+ type guard ring region 8 with an inner diameter of 18 μm and an outer diameter of 20 μm on the surface of the unintentionally doped indium phosphide multiplication layer 6 by selective doping technology, and the two are concentric;

[0015] The third step is to prepare a concentric annular isolation groove 9 with an inner diameter of 25 μm and an outer diameter of 30 μm outside the annular p+ type protection ring area 8 by using passivation, photolithography and etching processes;

[0016] In the fourth step, a metal film deposition, photolithography and etching process are used to prepare the Au front electrode 10 and the Au back electrode 11 to form a planar / table composite Geiger avalanche diode.

[0017] (III) Beneficial effects

[0018] The InGaAsP Geiger avalanche diode and its preparation method provided by the above technical solution have the following beneficial effects:

[0019] (1) By adopting an InGaAsP absorption layer with enhanced absorption at 1.06μm wavelength and a gradient-doped InGaAsP transition layer with a gradual doping concentration, the absorption of incident light in the short-wave infrared band with a wavelength of 1.06μm is improved, and the free space charge accumulation phenomenon caused by the difference in material band gap is reduced, thus solving the problem of low and slow response of traditional InGaAs Geiger avalanche diodes at a wavelength of 1.06μm.

[0020] (2) An innovative absorption multiplication separation structure is proposed, which uses gradient-doped InGaAsP as a transition layer. By preparing a transition layer with a gradient doping concentration, the energy band bending is achieved, which partially reduces the interfacial charge barrier caused by the difference in bandgap width between InGaAsP and InP. The photogenerated carriers can pass through the interface quickly, thus improving the device's ability to collect photogenerated carriers after ionization.

[0021] (3) It can provide a reference for designing and preparing InGaAsP Geiger avalanche diodes. The InGaAsP Geiger avalanche diode prepared according to the present invention achieves a high quantum efficiency absorption of more than 80% at a wavelength of 1.06 μm and a time resolution of less than 0.1 ns. This method is feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the materials for the InGaAsP Geiger avalanche diode.

[0023] Figure 2 Schematic diagram of the chip structure of the InGaAsP Geiger avalanche diode.

[0024] Figure 3 Schematic diagram of the gradient doped transition layer of the InGaAsP Geiger avalanche diode.

[0025] Figure 4 Schematic diagram of the relationship between the electric field strength and depth of the gradient-doped transition layer of the InGaAsP Geiger avalanche diode. DETAILED DESCRIPTION

[0026] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0027] The present invention provides an InGaAsP Geiger avalanche diode, which is a novel absorption multiplication separation avalanche diode structure with unintentionally doped InGaAsP as an absorption layer, unintentionally doped InGaAsP as a multiplication layer, highly uniformly doped InGaAsP as a charge layer, and gradient doped InGaAsP as a transition layer. The present invention designs an InGaAsP absorption layer with enhanced absorption at a wavelength of 1.06μm, and simultaneously achieves a high lattice matching with the InGaAsP multiplication layer, thereby reducing material defects of heteroepitaxial growth; designs a gradient doped InGaAsP transition layer with a doping concentration gradient feature, thereby reducing the interface charge barrier effect and increasing the drift velocity of carriers at the interface.

[0028] like Figure 1 and Figure 2 As shown, in the InGaAsP Geiger avalanche diode, heteroepitaxial technologies such as MBE or MOCVD are used to sequentially epitaxially grow n + type indium phosphide buffer layer 2, unintentionally doped indium gallium arsenic phosphide absorption layer 3, gradient doped indium gallium arsenic phosphide transition layer 4, n + type indium phosphorus charge layer 5, unintentionally doped indium phosphorus multiplication layer 6; using dielectric film deposition, photolithography, and high-temperature diffusion processes, a circular p-type indium phosphorus charge layer 5 is formed on the surface of the unintentionally doped indium phosphorus multiplication layer 6 by selective doping technology + Type doping region 7, annular p + Type guard ring area 8, the two are concentric; passivation, photolithography, etching process, in the ring p + A concentric annular isolation groove 9 is prepared outside the type guard ring area 8; a front electrode 10 and a back electrode 11 are prepared by using metal film deposition, photolithography and etching processes to form a planar / table composite Geiger avalanche diode.

[0029] like Figure 3 As shown, the impurity doping type of the gradient doped InGaAsP transition layer 4 is n-type, and the impurity doping concentration is from the gradient doped InGaAs transition layer 4 to n-type. + 2.0×10 at the interface of type indium phosphide charge layer 5 17 cm -3 The thickness of the interface between the gradient doped InGaAs transition layer 4 and the unintentionally doped InGaAsP absorption layer 3 is 1.0×10 17 cm -3 The thickness of the gradient-doped InGaAs transition layer 4 is 0.1-0.2 μm.

[0030] The composition of the unintentionally doped InGaAsP absorption layer 3 can be adjusted according to the wavelength of the laser to be measured. For example, if the laser wavelength is 1.06 μm, the composition of the corresponding InGaAsP absorption layer is In 0.85 GaAs 0.33 P.

[0031] Highly uniformly doped InP as n +The type indium phosphorus charge layer 5 has an impurity doping type of n type and an impurity doping concentration of 1.5 to 2.0×10 17 cm -3 , the charge layer thickness is 0.1~0.2μm.

[0032] like Figure 4 As shown, the avalanche zone L A The electric field strength is the Geiger avalanche electric field strength E J , charge region L P The electric field strength is from the Geiger avalanche electric field strength E J Change to avalanche breakdown electric field strength E MAX , gradient doping transition region L M The electric field strength of the avalanche breakdown electric field strength E MAX Change to saturation drift electric field strength E D , absorption zone L B The electric field strength drifts from the saturation electric field strength E D Change to the substrate electric field strength E S By gradient doping the transition layer, the carrier drift time is effectively reduced, and efficient and rapid detection of short-wave infrared single-photon weak signals is achieved.

[0033] Based on the structure of the InGaAsP Geiger avalanche diode, in the preparation method of the InGaAsP Geiger avalanche diode in this embodiment, an InGaAsP / InP multilayer heteroepitaxial material with an absorption multiplication charge transition separation structure having unintentionally doped InGaAsP as an absorption layer, unintentionally doped InGaAsP as a multiplication layer, highly uniformly doped InGaAsP as a charge layer, and gradient doped InGaAsP as a transition layer is prepared based on a 2-inch InGaAsP substrate, and a planar / table composite InGaAsP Geiger avalanche diode is prepared accordingly.

[0034] Specifically, the preparation method comprises the following steps:

[0035] In the first step, MOCVD deposition equipment is used on the indium phosphide substrate 1 to sequentially epitaxially grow the thickness to 0.5 μm and the doping concentration to 1E18 cm -3 n+ type indium phosphorus buffer layer 2, composition is In0.85GaAs0.33P, thickness is 2μm, unintentionally doped indium gallium arsenic phosphorus absorption layer 3, thickness is 0.1μm, doping concentration is 1.0-2.0E17cm -3 Gradient doped InGaAsP transition layer 4, thickness 0.1μm, doping concentration 2E17cm -3 n+ type indium phosphide charge layer 5, non-intentionally doped indium phosphide multiplication layer 6 with a thickness of 3.5 μm, see attached Figure 1 ; The impurity doping type of the gradient doped InGaAsP transition layer 4 is n-type, and the impurity doping concentration is from 2.0×10 17 cm-3 The thickness of the interface between the gradient doped InGaAs transition layer 4 and the unintentionally doped InGaAsP absorption layer 3 is 1.0×10 17 cm -3 The thickness of the gradient doped InGaAs transition layer 4 is 0.1 μm, see the attached Figure 3 .

[0036] In the second step, dielectric film deposition, photolithography, high temperature diffusion and other processes are used to form a circular p+ type doped region 7 with a diameter of 15 μm and an annular p+ type guard ring region 8 with an inner diameter of 18 μm and an outer diameter of 20 μm on the surface of the unintentionally doped indium phosphorus multiplication layer 6 by selective doping technology. The two are concentric, see attached Figure 2 ;

[0037] In the third step, a concentric annular isolation groove 9 with an inner diameter of 25 μm and an outer diameter of 30 μm is prepared outside the annular p+ type protection ring area 8 by passivation, photolithography and etching processes, as shown in the attached Figure 2 ;

[0038] The fourth step is to prepare the Au front electrode 10 and the Au back electrode 11 by metal film deposition, photolithography and etching process to form a planar / table composite Geiger avalanche diode, see attached Figure 2 .

[0039] During the preparation method, heteroepitaxial technologies such as MBE or MOCVD are used to prepare the aforementioned structure on an indium phosphide substrate according to specific structural parameters, and the interface interruption method is used to control the material growth quality at the interface of each functional layer. If MBE equipment is used, the corresponding beam source furnace should be turned off at this time, and rapid thermal annealing at a temperature not higher than 500°C for 30s to 60s should be adopted. If MOCVD equipment is used, the corresponding process gas should be turned off at this time, and the protective gas should continue to be introduced to reduce the generation of interface states.

[0040] After testing and evaluation, the planar / table composite InGaAsP Geiger avalanche diode prepared according to the gradient doping transition layer design and preparation method of the InGaAsP Geiger avalanche diode of the present invention has a quantum efficiency of 80% at 1.06μm and a time resolution of 0.1ns, achieving high sensitivity and fast response in the 1.06μm wavelength short-wave infrared band.

[0041] It can be seen from the above technical scheme that the present invention adopts a new structure of unintentionally doped InGaAsP as an absorption layer, unintentionally doped InGaAsP as a multiplication layer, highly uniformly doped InGaAsP as a charge layer, and gradient-doped InGaAsP as a transition layer. By adjusting the InGaAsP component, the light absorption efficiency of a wavelength of 1.06 μm is effectively improved. By gradient-doping the transition layer, the carrier drift time is effectively reduced. By increasing the bandgap width of the material, the operating temperature of the device is effectively increased. Without the need for deep refrigeration temperature control conditions, efficient and rapid detection of short-wave infrared single-photon weak signals at a wavelength of 1.06 μm can be achieved, which solves the problem of low and slow response of traditional InGaAs Geiger avalanche diodes at a wavelength of 1.06 μm, and meets the ultra-high sensitivity photoelectric detection requirements of weak light signals at the single-photon level.

[0042] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An InGaAsP Geiger avalanche diode, characterized in that: The invention comprises an indium phosphide substrate (1) and n-type epitaxial layers sequentially grown on the indium phosphide substrate (1). + type indium phosphide buffer layer (2), an unintentionally doped indium gallium arsenic phosphide absorption layer (3), a gradient doped indium gallium arsenic phosphide transition layer (4), n + type indium phosphorus charge layer (5), an unintentionally doped indium phosphorus multiplication layer (6); the surface of the unintentionally doped indium phosphorus multiplication layer (6) is formed into a circular p + Type doped region (7), annular p + Type protection ring area (8), the two are concentric; in the ring p + A concentric annular isolation groove (9) is prepared outside the type protection ring area (8); a front electrode (10) and a back electrode (11) are prepared to form a planar / table composite Geiger avalanche diode.

2. The InGaAsP Geiger avalanche diode according to claim 1, characterized in that: The impurity doping type of the gradient doped indium gallium arsenic phosphorus transition layer (4) is n-type, and the impurity doping concentration increases from the gradient doped indium gallium arsenic transition layer (4) to the n-type. + 2.0×10 at the interface of indium phosphide charge layer (5) 17 cm -3 The interface between the gradient-doped InGaAs transition layer (4) and the unintentionally doped InGaAsP absorption layer (3) is 1.0×10 17 cm -3 .

3. The InGaAsP Geiger avalanche diode according to claim 2, characterized in that: The thickness of the gradient doped InGaAs transition layer (4) is 0.1-0.2 μm.

4. The InGaAsP Geiger avalanche diode according to claim 2, characterized in that: The composition of the unintentionally doped InGaAsP absorption layer (3) is adjusted according to the wavelength of the laser to be measured. When the laser wavelength is 1.06 μm, the composition of the corresponding InGaAsP absorption layer is In 0.85 GaAs 0.33 P.

5. The InGaAsP Geiger avalanche diode according to claim 3, characterized in that: Highly uniformly doped InP as n + The indium phosphorus charge layer (5) has an n-type impurity doping type and an impurity doping concentration of 1.5 to 2.0×10 17 cm -3 .

6. The InGaAsP Geiger avalanche diode according to claim 5, characterized in that: n + The thickness of the indium phosphide charge layer (5) is 0.1 to 0.2 μm.

7. A method for preparing the InGaAsP Geiger avalanche diode according to claim 6, characterized in that: Based on a 2-inch indium phosphide substrate, an indium gallium arsenic phosphide / indium phosphide multilayer heteroepitaxial material with an absorption multiplication charge transition separation structure having unintentionally doped indium gallium arsenic phosphide as an absorption layer, unintentionally doped indium phosphide as a multiplication layer, highly uniformly doped indium phosphide as a charge layer, and gradient doped indium gallium arsenic phosphide as a transition layer was prepared. Based on this, a planar / table-type composite indium gallium arsenic phosphide Geiger avalanche diode was prepared.

8. The preparation method according to claim 7, characterized in that: The preparation process of the multilayer heteroepitaxial material is as follows: using MOCVD deposition equipment on an indium phosphide substrate (1), sequentially epitaxially depositing layers with a thickness of 0.5 μm and a doping concentration of 1E18 cm -3 The n+ type indium phosphorus buffer layer (2) has a composition of In0.85GaAs0.33P and a thickness of 2 μm, and the non-intentionally doped indium gallium arsenic phosphorus absorption layer (3) has a thickness of 0.1 μm and a doping concentration of 1.0-2.0E17cm -3 A gradient doped indium gallium arsenic phosphorus transition layer (4) with a thickness of 0.1 μm and a doping concentration of 2E17 cm -3 An n+ type indium phosphide charge layer (5) and an unintentionally doped indium phosphide multiplication layer (6) with a thickness of 3.5 μm.

9. The preparation method according to claim 8, characterized in that: The impurity doping type of the gradient doped indium gallium arsenic phosphide transition layer (4) is n-type, and the impurity doping concentration increases from 2.0×10 17 cm -3 The interface between the gradient-doped InGaAs transition layer (4) and the unintentionally doped InGaAsP absorption layer (3) is 1.0×10 17 cm -3 The thickness of the gradient doped InGaAs transition layer (4) is 0.1 μm.

10. The preparation method according to claim 9, characterized in that: Also includes: A dielectric film deposition, photolithography, and high-temperature diffusion process is adopted to form a circular p+ type doping area (7) with a diameter of 15 μm and an annular p+ type protection ring area (8) with an inner diameter of 18 μm and an outer diameter of 20 μm on the surface of an unintentionally doped indium phosphorus multiplication layer (6) by selective area doping technology, and the two are concentric; a passivation, photolithography, and etching process is adopted to prepare a concentric annular isolation groove (9) with an inner diameter of 25 μm and an outer diameter of 30 μm outside the annular p+ type protection ring area (8); and a metal film deposition, photolithography, and etching process is adopted to prepare an Au front electrode (10) and an Au back electrode (11), thereby forming a planar / table composite Geiger avalanche diode.

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