Expansion short wave infrared detector of lattice matching InP substrate

Abstract

The invention discloses an expanded short wave infrared detector of a lattice matching InP substrate, and relates to the technical field of infrared detectors. The infrared detector comprises a P layer, an N layer and an absorption layer arranged between the P layer and the N layer. The absorption layer is a BGaInAs quaternary compound of which the lattice constant is matched with that of the InP substrate, the B component range is 0-0.15, the forbidden bandwidth range is 0.36-0.75 eV, and the cut-off wavelength range is 1.7-3.4 [mu] m. According to the invention, the cut-off wavelength can be detected to 3 microns without a stress buffer layer, and high responsivity and high quantum efficiency are achieved. Wherein the peak responsivity is not lower than 1.3 A / W, and the peak quantum efficiency is not lower than 70%; at the cut-off wavelength of 3 microns, the responsivity is not lower than 1A / W, the quantum efficiency is not lower than 40%, and the detection performance is excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared detectors, and specifically to an extended short-wave infrared detector with a lattice-matched InP substrate. Background Art

[0002] The short-wave infrared (SWIR) wavelength range is from 1 to 3 micrometers, which is one of the important infrared atmospheric windows. Due to the unique spectral characteristics of many substances in the SWIR band, SWIR imaging technology has wide applications in military, agricultural, industrial, medical and other fields.

[0003] A SWIR detector can convert the collected infrared radiation into a processable electrical signal, and is the core device of SWIR imaging technology. The indium gallium arsenide (InGaAs) SWIR detector based on an indium phosphide (InP) substrate has the advantages of high sensitivity, high stability, high uniformity, and operability at room temperature, and is one of the ideal choices for SWIR detectors.

[0004] Considering the substrate lattice matching problem, when the absorption layer composition is In 0.53 Ga 0.47 As, its lattice constant matches that of the InP substrate. However, the bandgap of In 0.53 Ga 0.47 As is 0.75 eV, and the detection cut-off wavelength is only 1.7 μm, which fails to cover the SWIR wavelength range.

[0005] When the cut-off wavelength is in the range of 1.7 to 3 μm, the corresponding device is called an extended SWIR detector. By increasing the In content to 0.83, that is, the absorption layer composition is In 0.83 Ga 0.17 As, the detection cut-off wavelength can be extended to 2.6 μm; however, at this time, the lattice constant of the absorption layer In 0.83 Ga 0.17 As is The lattice mismatch with the InP substrate (lattice constant is ) can reach 2%, which directly affects the optical and electrical quality of the absorption layer thin film, and further limits the detection performance of the device.

[0006] Therefore, the existing extended SWIR detectors with an InGaAs absorption layer have lattice mismatch and thus poor detection performance.

[0007] How to design and develop a SWIR detector with a lattice-matched InP substrate and a detection wavelength extended to 3 μm is a problem to be urgently solved. Summary of the Invention

[0008] The present invention aims to solve the problem that the detection performance of existing extended SWIR detectors with InGaAs absorption layers is poor due to lattice mismatch. The present invention provides an extended short-wave infrared detector with a lattice-matched InP substrate. By doping boron in the absorption layer InGaAs to balance the lattice expansion phenomenon caused by a high In component, a new high-performance SWIR detector with a lattice-matched InP substrate and a detection wavelength extended to 3 μm is designed. When the wavelength is 3 μm, the responsivity is not less than 1 A / W, and the quantum efficiency is not less than 40%.

[0009] To achieve the above object, the present invention specifically adopts the following technical solutions:

[0010] The present invention provides an extended short-wave infrared detector with a lattice-matched InP substrate, which includes a P layer, an N layer, and an absorption layer disposed between the P layer and the N layer.

[0011] Further, the absorption layer is a BGaInAs quaternary compound with a lattice constant matching that of the InP substrate.

[0012] Further, the B component range of the BGaInAs quaternary compound is 0 to 0.15, the bandgap width range is 0.36 to 0.75 eV, and the cut-off wavelength range is 1.7 to 3.4 μm.

[0013] Further, the absorption layer is lightly doped n-type B 0.135 Ga 0.045 In 0.82 As.

[0014] Further, the electron doping concentration range of the absorption layer is 1×10 15 ~5×10 16 cm -3 .

[0015] Further, the thickness of the absorption layer is 2.6 to 5 μm.

[0016] Further, the P layer and the N layer are heavily doped InP layers.

[0017] Further, the hole doping concentration range of the P layer is 4×10 19 ~1×10 20 cm -3 .

[0018] Further, the electron doping concentration range of the N layer is 1×10 18 ~1×10 20 cm -3 .

[0019] Further, the thicknesses of the P layer and the N layer are 1 μm.

[0020] Compared with the prior art, the advantages of the present invention are as follows:

[0021] 1. An extended short-wave infrared detector with a lattice-matched InP substrate according to the present invention effectively adjusts the lattice constant of the absorption layer by doping a small amount of boron (B) into the absorption layer InGaAs with a high In composition to balance the lattice expansion phenomenon caused by the high In composition. While the bandgap width of the absorption layer meets 0.41 eV (cutoff wavelength is 3 μm), the lattice mismatch problem between the absorption layer and the InP substrate is solved; secondly, a lattice-matched BGaInAs quaternary compound is used as the detector absorption layer, and by adjusting the doping concentration, thickness of the detector absorption layer, and the doping concentration of the P / N layer, high responsivity and high quantum efficiency are achieved in the 1 - 3 μm band. A novel high-performance SWIR detector with a lattice-matched InP substrate and an extended detection wavelength up to 3 μm is designed. When the wavelength is 3 μm, the responsivity is not less than 1 A / W, and the quantum efficiency is not less than 40%. Brief Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of an extended short-wave infrared detector with a lattice-matched InP substrate according to the present invention.

[0023] Figure 2 It is a schematic structural diagram of the extended short-wave infrared detector 1 with a lattice-matched InP substrate provided in Embodiment 1 of the specification.

[0024] Figure 3 It is a schematic diagram of the curve of the detector responsivity of the extended short-wave infrared detector 1 with a lattice-matched InP substrate changing with wavelength in Test Example 1 of the specification.

[0025] Figure 4 It is a schematic diagram of the curve of the detector quantum efficiency of the extended short-wave infrared detector 1 with a lattice-matched InP substrate changing with wavelength in Test Example 1 of the specification.

[0026] Reference Numerals in the Drawings: 1 - P layer, 2 - absorption layer, 3 - N layer.

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0028] Therefore, the following detailed description of the provided embodiments of the present invention is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. Detailed implementation manners

[0029] The present invention provides an extended short-wave infrared detector with a lattice-matched InP substrate. Please refer to Figure 1 the structural diagram of

[0030] In some embodiments of the present invention, please refer to Figure 2 in combination, the absorption layer 2 is a BGaInAs quaternary compound with a lattice constant matching that of the InP substrate.

[0031] In some embodiments of the present invention, please continue to refer to Figure 2 in combination, the B component range of the BGaInAs quaternary compound is 0 to 0.15, the bandgap width range is 0.36 to 0.75 eV, and the cut-off wavelength range is 1.7 to 3.4 μm.

[0032] In some embodiments of the present invention, please continue to refer to Figure 2 in combination, the absorption layer 2 is lightly doped n-type B 0.135 Ga 0.045 In 0.82 As.

[0033] In some embodiments of the present invention, please continue to refer to Figure 2 in combination, the electron doping concentration range of the absorption layer 2 is 1×10 15 to 5×10 16 cm -3 .

[0034] In some embodiments of the present invention, please continue to refer to Figure 2 in combination, the thickness of the absorption layer 2 is 2.6 to 5 μm.

[0035] It can be understood that, please continue to refer to Figure 1 in combination, the extended short-wave infrared detector with a lattice-matched InP substrate in the embodiments of the present invention includes a P layer 1, an N layer 3, and an absorption layer 2 disposed between the P layer 1 and the N layer 3, which is a PIN device structure with stable structure and excellent detection performance. Specifically, the detection cut-off wavelength can reach 3 μm without a stress buffer layer, and it has high responsivity and high quantum efficiency. Among them, the peak responsivity is not less than 1.3 A / W, and the peak quantum efficiency is not less than 70%; at the cut-off wavelength of 3 μm, the responsivity is not less than 1 A / W, and the quantum efficiency is not less than 40%.

[0036] It should be further clarified that the absorption layer 2 of the extended short-wave infrared detector, as the core region for the detector to achieve optoelectronic conversion, the magnitude of its bandgap directly affects the detection band of the device. When the detection cut-off wavelength is 3 μm, the bandgap of the absorption layer 2 is approximately 0.41 eV.

[0037] The ternary compound InGaAs with a high In composition can achieve a bandgap of 0.41 eV. However, it has obvious defects and a large lattice constant, making it difficult to match the lattice constant of the InP substrate.

[0038] The B atom has a small atomic radius. Therefore, in the extended short-wave infrared detector of the present invention's embodiment that is lattice-matched to the InP substrate, by doping with B, the lattice expansion phenomenon caused by the high In composition can be balanced by boron atoms, thus well matching the lattice constant of the InP substrate.

[0039] Furthermore, according to Vegard's law, first calculate the relationship between the lattice constant of the B x Ga y In 1-x-y As quaternary compound and the change of its composition.

[0040] Then, based on the Moon energy band calculation model of the present invention, considering the energy band bending coefficient, calculate the relationship between the bandgap of the B x Ga y In 1-x-y As quaternary compound and the change of its composition. The calculation formula is as follows:

[0041] E(x,y) = xE BAs +yE GaAs +(1 - x - y)E InAs -xyC BGaAs -x(1 - x - y)C BInAs -y(1 - x - y)C GaInAs

[0042] Among them, E BAs is the bandgap of the BAs compound, E GaAs is the bandgap of the GaAs compound, E InAs is the bandgap of the InAs compound, C BGaAs is the bending coefficient between the BAs compound and the GaAs compound, C BInAs is the bending coefficient between the BAs compound and the InAs compound, C GaInAs is the bending coefficient between the GaAs compound and the InAs compound.

[0043] According to the calculation results, when lattice-matched to the InP substrate, B x Ga y In1-x-y In the quaternary compound, the range of the B component is 0 to 0.15, the band gap width range is 0.36 to 0.75 eV, and the cut-off wavelength range is 1.7 to 3.4 μm. When the component of the absorption layer 2 is B 0.135 Ga 0.045 In 0.82 As, the band gap width is 0.4 eV, and the cut-off wavelength can be extended to 3 μm.

[0044] That is, in the extended short-wave infrared detector with a lattice-matched InP substrate in the embodiment of the present invention, by doping a small amount of B boron into the high-In component absorption layer 2 InGaAs to balance the lattice expansion phenomenon caused by the high-In component, the lattice constant of the absorption layer 2 is effectively adjusted.

[0045] First, while the band gap width of the absorption layer 2 satisfies 0.41 eV (cut-off wavelength is 3 μm), the lattice mismatch problem between the absorption layer 2 and the InP substrate is solved.

[0046] Secondly, using the lattice-matched BGaInAs quaternary compound as the detector absorption layer 2, by adjusting the doping concentration, thickness of the detector absorption layer 2, and the doping concentration of the P layer 1 / N layer 3, high responsivity and high quantum efficiency are achieved in the 1 to 3 μm band.

[0047] In some embodiments of the present invention, the P layer 1 and the N layer 3 are heavily doped InP layers.

[0048] In some embodiments of the present invention, please continue to refer to Figure 2 , the hole doping concentration range of the P layer 1 is 4×10 19 ~1×10 20 cm -3 .

[0049] In some embodiments of the present invention, please continue to refer to Figure 2 , the electron doping concentration range of the N layer 3 is 1×10 18 ~1×10 20 cm -3 .

[0050] In some embodiments of the present invention, please continue to refer to Figure 2 , the thicknesses of the P layer 1 and the N layer 3 are 1 μm.

[0051] Embodiment 1

[0052] In this embodiment, an extended short-wave infrared detector 1 with a lattice-matched InP substrate is provided. Please refer to the structural schematic diagram in Figure 1 . The infrared detector includes a P layer 1, an N layer 3, and an absorption layer 2 disposed between the P layer 1 and the N layer 3.

[0053] Please refer to Figure 1 and Figure 2 , the P layer and the N layer are heavily doped InP layers, and the hole doping concentration range of the P layer is 4×10 19 ~1×10 20 cm -3 . The electron doping concentration range of the N layer is 1×10 18 ~1×10 20 cm -3 . The thicknesses of the P layer and the N layer are 1 μm.

[0054] Among them, please continue to refer to Figure 2 , the absorption layer is lightly doped n-type B 0.135 Ga 0.045 In 0.82 As. The electron doping concentration range is 1×10 15 ~5×10 16 cm -3 . The thickness of the absorption layer is 2.6 - 5 μm.

[0055] Test Example 1

[0056] 1.1 Test operation

[0057] Take the extended short-wave infrared detector 1 obtained in Example 1 and measure the curve of its responsivity versus wavelength under the condition of a -0.1 V bias voltage. The measurement results are shown in Figure 3 .

[0058] 1.2 Analysis of test results

[0059] Please refer to Figure 3 , the peak responsivity of the extended short-wave infrared detector 1 obtained in Example 1 is not less than 1.3 A / W.

[0060] And at the cut-off wavelength of 3 μm, the responsivity of the extended short-wave infrared detector 1 obtained in Example 1 is not less than 1 A / W, having good detection performance.

[0061] Test Example 2

[0062] 2.1 Test operation

[0063] Take the extended short-wave infrared detector 1 obtained in Example 1 and measure the curve of its quantum efficiency versus wavelength under the condition of a -0.1 V bias voltage. The measurement results are shown in Figure 4 .

[0064] 2.2 Analysis of test results

[0065] Please refer to Figure 4, the peak quantum efficiency of the extended short-wave infrared detector 1 obtained in Example 1 is not less than 70%.

[0066] And at the cut-off wavelength of 3 μm, the quantum efficiency of the extended short-wave infrared detector 1 obtained in Example 1 is not less than 40%, showing excellent performance.

[0067] In summary, the structure of the extended short-wave infrared detector with a lattice-matched InP substrate of the present invention is stable and has excellent detection performance. According to the implementation and tests of Examples 1-2 and Test Examples 1-2, it can be seen that the extended short-wave infrared detector of the present invention can achieve a detection cut-off wavelength of up to 3 μm without a stress buffer layer, and has high responsivity and high quantum efficiency.

[0068] And according to the measurement of the test example and combined with the participation Figure 3 and Figure 4 , the peak responsivity of the extended short-wave infrared detector of the present invention is not less than 1.3 A / W, and the peak quantum efficiency is not less than 70%; at the cut-off wavelength of 3 μm, the responsivity is not less than 1 A / W, and the quantum efficiency is not less than 40%, with excellent detection performance and a relatively wide application space. Moreover, the device structure of the extended short-wave infrared detector of the present invention is simple and is easy to be widely applied and promoted.

[0069] The above embodiments are only one implementation manner of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the appended claims.

Claims

1. An extended short-wave infrared detector based on a lattice-matched InP substrate, characterized in that: The infrared detector comprises a P layer, an N layer and an absorption layer arranged between the P layer and the N layer.

2. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 1, characterized in that: The absorption layer is a BGaInAs quaternary compound whose lattice constant matches that of the InP substrate.

3. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 2, characterized in that: The B component of the BGaInAs quaternary compound ranges from 0 to 0.15, the bandgap width ranges from 0.36 to 0.75 eV, and the cutoff wavelength ranges from 1.7 to 3.4 μm.

4. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 1, characterized in that: The absorption layer is lightly doped n-type B 0.135 Ga 0.045 In 0.82 As.

5. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 4, characterized in that: The electron doping concentration of the absorption layer is in the range of 1×10 15 ~5×10 16 cm -3 .

6. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 4, characterized in that: The thickness of the absorption layer is 2.6-5 μm.

7. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 1, characterized in that: The P layer and the N layer are heavily doped InP layers.

8. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 7, characterized in that: The hole doping concentration of the P layer is in the range of 4×10 19 ~1×10 20 cm -3 .

9. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 7, characterized in that: The electron doping concentration of the N layer is in the range of 1×10 18 ~1×10 20 cm -3 .

10. The extended short-wave infrared detector based on a lattice-matched InP substrate according to claim 1, characterized in that: The thickness of the P layer and the N layer is 1 μm.

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