Long-wave infrared detector with improved quantum efficiency

Abstract

The application relates to the field of detectors, and provides a long-wave infrared detector with improved quantum efficiency, wherein the long-wave infrared detector with improved quantum efficiency comprises: a potential barrier layer epitaxially arranged on a bottom contact layer; an absorption layer epitaxially arranged on the potential barrier layer; and a top contact layer epitaxially arranged on the absorption layer; the InAs layer thicknesses of the potential barrier layer, the bottom contact layer, the absorption layer and the top contact layer are different, and the GaSb / AlSb / GaSb layer thicknesses are the same. The long-wave infrared detector with improved quantum efficiency provided by the application solves the defects in the prior art that the long-wave infrared detector is limited by high dark current noise and thus the performance is damaged. The potential barrier layer is arranged between the bottom contact layer and the absorption layer, the InAs layer thicknesses of the potential barrier layer and other layers are adjusted, the lattice mismatch problem is reduced to the maximum extent, the valence band offset between the bottom contact layer, the potential barrier layer, the absorption layer and the top contact layer is reduced, the dark current noise is reduced, and the quantum efficiency of the detector is improved.

Description

Technical Field

[0001] This invention relates to the field of detector technology, and in particular to a long-wave infrared detector with improved quantum efficiency. Background Technology

[0002] The long wavelength infrared (LWIR) band, with wavelengths above 8μm, has a wide range of applications in both military and civilian fields, including thermal imaging and night vision, security and military applications, medical applications, industrial and testing, spectral imaging, component testing, and environmental monitoring.

[0003] For long-wave infrared detectors, the high light absorption coefficient of the absorption region material is the foundation for the high quantum efficiency of optoelectronic devices, and the dark current and quantum efficiency of the device are important standards for measuring detector performance. Most superlattice barrier detectors use bulk materials or superlattice materials different from the absorption layer as the barrier layer. The resulting lattice mismatch affects the epitaxial growth of the crystal to varying degrees, generating a large number of defects during material growth, which affects the sensitivity of the long-wave infrared detector, i.e., the quantum efficiency. Summary of the Invention

[0004] This invention provides a long-wave infrared detector with improved quantum efficiency, which solves the problem that the quantum efficiency performance of existing long-wave infrared detectors is limited by high dark current noise, resulting in performance degradation. It reduces the valence band offset between the barrier layer and the absorption layer, the top contact layer, and the bottom contact layer, thereby reducing noise and improving the quantum efficiency of the detector.

[0005] This invention provides a long-wavelength infrared detector with improved quantum efficiency, comprising:

[0006] Bottom contact layer;

[0007] A barrier layer, the barrier layer extending over the bottom contact layer;

[0008] An absorption layer, which is epitaxial on the barrier layer;

[0009] A top contact layer extending beyond the absorbent layer;

[0010] The bottom contact layer, the barrier layer, the absorption layer, and the top contact layer are all M-type superlattices of InAs / GaSb / AlSb / GaSb. The InAs layer of the barrier layer has a different thickness than that of the bottom contact layer, the absorption layer, and the top contact layer, while the GaSb / AlSb / GaSb layers have the same thickness.

[0011] The long-wave infrared detector with improved quantum efficiency provided by the present invention further includes:

[0012] Substrate layer;

[0013] A buffer layer is epitaxially mounted on the substrate layer, and a bottom contact layer is epitaxially mounted on the buffer layer. The buffer layer has a doping concentration greater than 1 × 10⁻⁶. 18 cm -3 , used to prepare ohmic contacts;

[0014] A capping layer, extending beyond the top contact layer, has a doping concentration greater than 1 × 10⁻⁶. 18 cm -3 , used to prepare ohmic contacts.

[0015] According to the quantum-efficient long-wave infrared detector provided by the present invention, the cutoff wavelength of the superlattice material of the absorption layer corresponds to the long-wave infrared band of 8μm to 12μm, and the thickness is 1-3 micrometers.

[0016] According to the quantum-efficient long-wave infrared detector provided by the present invention, the cutoff wavelength of the superlattice material of the bottom contact layer and the top contact layer is the same as that of the absorption layer, and the thickness is less than 1 micrometer.

[0017] According to the long-wave infrared detector for improved quantum efficiency provided by the present invention, the cutoff wavelength of the superlattice material of the barrier layer is in the mid-infrared band, and the thickness is less than 500 nanometers.

[0018] According to the long-wave infrared detector with improved quantum efficiency provided by the present invention, the buffer layer and the capping layer are both heavily n-type doped, with doping concentrations greater than 1×10⁻⁶. 18 cm -3 .

[0019] According to the long-wave infrared detector with improved quantum efficiency provided by the present invention, the bottom contact layer and the top contact layer are n-type doped with a doping concentration of 1×10⁻⁶. 17 -1×10 18 cm -3 .

[0020] According to the long-wave infrared detector with improved quantum efficiency provided by the present invention, the barrier layers are all unintentionally doped, exhibiting weak p-type doping, with a doping concentration of 1×10⁻⁶. 15 -1×10 16 cm -3 The absorber layer is a weakly n-type doped layer with a doping concentration of 5 × 10⁻⁶. 15 -5×10 16 cm -3 .

[0021] According to the long-wave infrared detector with improved quantum efficiency provided by the present invention, the conduction band vacuum energy level of the barrier layer is more than 150 meV higher than the conduction band vacuum energy level of the absorption layer, and the difference between the valence band vacuum energy level of the barrier layer and the valence band vacuum energy level of the absorption layer is less than 10 meV.

[0022] According to the long-wave infrared detector with improved quantum efficiency provided by the present invention, the band gap of the barrier layer is more than 170 meV higher than the band gap of the absorption layer.

[0023] The long-wave infrared detector with improved quantum efficiency provided by the present invention further includes:

[0024] The first passivation layer is disposed on the outermost periphery above the buffer layer and is in the form of an annular protrusion.

[0025] The second passivation layer is disposed above the buffer layer and wraps around the outermost periphery of the bottom contact layer, the absorption layer, the barrier layer, the top contact layer and part of the capping layer;

[0026] The first electrode is disposed above the buffer layer and adjacent to the first passivation layer and the second passivation layer;

[0027] The second electrode is disposed above the capping layer and adjacent to the inner side of the second passivation layer, and is in the form of an annular protrusion.

[0028] The long-wave infrared detector with improved quantum efficiency provided by this invention reduces lattice mismatch to the greatest extent by placing a barrier layer between the bottom contact layer and the absorption layer, and by adjusting the thickness of the InAs layer between the barrier layer and other layers. This reduces the valence band offset between the bottom contact layer, the barrier layer, the absorption layer and the top contact layer, reduces dark current noise, and improves the quantum efficiency of the detection device. By adjusting the thickness of the InAs layer in the M-type superlattice structure, the cutoff wavelength of the absorption layer can be changed while keeping the valence band position basically unchanged. This allows for the design of long-wave detectors capable of detecting wavelengths from 8 μm to 12 μm. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the long-wave infrared detector with improved quantum efficiency provided by the present invention;

[0031] Figure 2This is a sub-band dispersion diagram of the absorption layer corresponding to different InAs thicknesses in the M-type superlattice at 77K according to the present invention;

[0032] Figure 3 This is a graph showing the absorption coefficient of the absorption layer corresponding to different InAs thicknesses in the M-type superlattice at 77K according to the present invention.

[0033] Figure 4 This invention provides a band structure for a long-wave infrared detector with improved quantum efficiency under a 0V bias voltage.

[0034] Figure 5 yes Figure 4 Quantum efficiency diagrams for two different long-wave infrared detector structures.

[0035] Figure label:

[0036] 100: Substrate layer; 101: Buffer layer; 102: Bottom contact layer; 103: Barrier layer; 104: Absorption layer; 105: Top contact layer; 106: Cap layer; 200: First passivation layer; 201: Second passivation layer; 300: First electrode; 301: Second electrode. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] In the description of the embodiments of the present invention, it should be noted that the terms "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0039] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0040] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0041] The following is combined Figures 1 to 5 The embodiments of the present invention will be described below. It should be understood that the following description is merely an illustrative embodiment of the present invention and does not constitute a limitation thereof.

[0042] like Figure 1 As shown, this invention provides a long-wavelength infrared detector with improved quantum efficiency, comprising: a bottom contact layer 102, a barrier layer 103, an absorption layer 104, and a top contact layer 105. The barrier layer 103 is epitaxially mounted on the bottom contact layer 102; the absorption layer 104 is epitaxially mounted on the barrier layer 103; and the top contact layer 105 is epitaxially mounted on the absorption layer 104. The bottom contact layer 102, barrier layer 103, absorption layer 104, and top contact layer 105 are all M-type superlattices of InAs / GaSb / AlSb / GaSb. The InAs layer thickness of the barrier layer 103 differs from that of the bottom contact layer 102, absorption layer 104, and top contact layer 105, while the GaSb / AlSb / GaSb layers have the same thickness. This design minimizes the lattice mismatch problem between the two different materials and maintains the valence band top at approximately the same position, reducing the difference in valence band vacuum energy levels between the barrier layer 103 and the absorption layer 104.

[0043] In other words, the bottom contact layer 102, barrier layer 103, absorber layer 104, and top contact layer 105 are stacked sequentially from bottom to top. All three layers are composed of group III-V antimonybide semiconductors, forming an M-type superlattice of InAs / GaSb / AlSb / GaSb, and are grown via molecular beam epitaxy. In this invention, the same superlattice structure is used for both the absorber layer 104 and the barrier layer 103 to minimize lattice mismatch. The key to barrier detector design is to maximize the conduction band offset between the barrier layer 103 and the absorber layer 104 to block electrons or holes, while minimizing the valence band offset. A large valence band offset (VBO) generates an electric field in the absorber layer 104 adjacent to the barrier layer 103, thus forming a depletion region and causing a GR current. By adjusting the thickness of the InAs layer in the M-type superlattice structure (InAs / GaSb / AlSb / GaSb), the cutoff wavelength of the absorption layer 104 can be changed while keeping the valence band position basically unchanged. This allows for the design of long-wavelength detectors ranging from 8 μm to 12 μm.

[0044] In this embodiment, the bottom contact layer 102, absorption layer 104, and top contact layer 105 all adopt a superlattice structure of the InAs / GaSb / AlSb / GaSb system with the same number of layers and period, in order to minimize lattice mismatch. Simultaneously, the superlattice structure can be controlled and adjusted through bandgap engineering to obtain a structure that better meets the requirements. The thickness of a single layer (ML) in the InAs / GaSb / AlSb / GaSb superlattice structure is the thickness of a lattice constant corresponding to InAs, GaSb, or AlSb. For example, the bottom contact layer 102, absorption layer 104, and top contact layer 105 can adopt a superlattice structure of InAs / GaSb / AlSb / GaSb with a layer period of 11 / 4 / 1 / 4MLs, meaning that the number of ML layers in InAs in this structure is 11. ML is a unit of layer number. One ML represents the thickness of one lattice constant. The lattice constants of InAs, GaSb, and AlSb are basically equal, approximately 0.61 nm.

[0045] Furthermore, in one embodiment of the present invention, the long-wavelength infrared detector with improved quantum efficiency further includes: a substrate layer 100, a buffer layer 101, and a capping layer 106. The buffer layer 101 is epitaxially grown on the substrate layer 100, and a bottom contact layer 102 is epitaxially grown on the buffer layer 101; the capping layer 106 is epitaxially grown on the top contact layer 105. The doping concentration of the buffer layer 101 is greater than 1 × 10⁻⁶. 18 cm -3It is used to prepare ohmic contacts, and the doping concentration of the capping layer 106 is greater than 1×10⁻⁶. 18 cm -3 , used to prepare ohmic contacts.

[0046] Specifically, on a Te-doped GaSb(100) substrate, an n-type heavily doped GaSb buffer layer 101, a bottom contact layer 102 of an n-type doped InAs / GaSb / AlSb / GaSb superlattice material, a barrier layer 103 of an unintentionally doped InAs / GaSb / AlSb / GaSb superlattice material, an absorption layer 104 of an n-type doped InAs / GaSb / AlSb / GaSb superlattice material, a top contact layer 105 of an n-type doped InAs / GaSb / AlSb / GaSb superlattice material, and a capping layer 106 of an n-type heavily doped InAs are sequentially grown; each segment of the superlattice material satisfies lattice matching between upper and lower layers and stress balance. The buffer layer 101 is introduced to minimize lattice mismatch problems during material growth.

[0047] In some embodiments of the present invention, the cutoff wavelength of the superlattice material of the absorption layer 104 corresponds to the long-wave infrared band of 8μm to 12μm, and the thickness is 1-3 micrometers.

[0048] In another embodiment of the present invention, the cutoff wavelength of the superlattice material of the bottom contact layer 102 and the top contact layer 105 is the same as that of the absorption layer 104, and the thickness is less than 1 micrometer.

[0049] In an optional embodiment of the present invention, the cutoff wavelength of the superlattice material of the barrier layer 103 is in the mid-infrared band, and the thickness is less than 500 nanometers.

[0050] Furthermore, in other embodiments of the present invention, the buffer layer 101 and the capping layer 106 are heavily n-type doped, with a doping concentration greater than 1 × 10⁻⁶. 18 cm -3 The purpose is to facilitate contact with the metal electrode to form an ohmic contact. Ohmic contacts are very important for semiconductor devices, and forming a good ohmic contact is beneficial for current input and output.

[0051] In an optional embodiment of the present invention, the barrier layer 103 is unintentionally doped, exhibiting weak p-type doping with a doping concentration of 1×10⁻⁶. 15 -1×10 16 cm -3 The absorber layer 104 is weakly n-type doped, with a doping concentration of 5 × 10⁻⁶. 15 -5×10 16 cm -3 Between. The top and bottom contact layers are n-type doped with a doping concentration of 1×10⁻⁶. 17 -1×1018 cm -3 Between. Both the substrate and the buffer layer 101 are n-type Te-doped GaSb(100) materials with a doping concentration greater than 1×10⁻⁶. 18 cm -3 Te-doped GaSb(100) substrates. The Te-doped GaSb(100) substrate layer 100 can be prepared by Czochralski method, Bridgman method, vertical gradient solidification method and moving heater method.

[0052] In other embodiments of the present invention, the conduction band vacuum level of the barrier layer 103 is more than 150 meV higher than the conduction band vacuum level of the absorption layer 104, and the difference between the valence band vacuum level of the barrier layer 103 and the valence band vacuum level of the absorption layer 104 is less than 10 meV.

[0053] In a specific embodiment of the present invention, the band gap of the barrier layer 103 is more than 170 meV higher than the band gap of the absorption layer 104.

[0054] By employing band engineering, the band gap and vacuum level positions of a superlattice are adjusted by modifying the composition and thickness within its periodicity. Then, using the eight-band k·p model theory, based on the Luttinger-Kohn and Bir-Pikus models, the band structure of the superlattice is calculated, including energy dispersion relations and wave functions. Furthermore, the optical absorption coefficient is calculated by representing matrix elements using optical dipole moments, allowing for the design of superlattice materials with different absorption cutoff wavelengths. This results in the conduction band vacuum level of barrier layer 103 being approximately 170 meV higher than that of absorption layer 104; the difference between the valence band vacuum level of barrier layer 103 and that of absorption layer 104 (VBO) is controlled within 10 meV; and the band gap of barrier layer 103 is more than 160 meV higher than that of absorption layer 104, thus achieving the function of blocking electrons.

[0055] Continue to refer to Figure 1 In other embodiments of the present invention, the long-wave infrared detector with improved quantum efficiency further includes: a first passivation layer 200, a second passivation layer 201, a first electrode 300, and a second electrode 301. The first passivation layer 200 is disposed on the outermost periphery above the buffer layer 101 and is in the form of an annular protrusion. The second passivation layer 201 is disposed above the buffer layer 101 and wraps around the outermost periphery of the bottom contact layer 102, the barrier layer 103, the absorption layer 104, the top contact layer 105, and part of the capping layer 106. The first electrode 300 is disposed above the buffer layer and is adjacent to the first passivation layer 200 and the second passivation layer 201. The second electrode 301 is disposed above the capping layer 106 and is adjacent to the inner side of the second passivation layer 201 and is in the form of an annular protrusion.

[0056] Specifically, a mesa region is etched to improve quantum efficiency in a long-wavelength infrared detector. A first passivation layer 200 and a second passivation layer 201, each 200-500 nm thick, are grown on the mesa structure. The materials of the first passivation layer 200 and the second passivation layer 201 include SiO2 or SiN. x The function is to protect the sidewalls and prevent oxidation of the device surface, thereby reducing surface leakage current. The patterns of the first electrode 300 and the second electrode 301 are transferred onto the sample, and ohmic contact electrodes are prepared after etching. The materials of the first electrode 300 and the second electrode 301 include Ti, Pt, Au, Cu, and Ni, and their function is to form ohmic contacts with the buffer layer 101 and the capping layer 106, respectively.

[0057] The present invention provides a long-wavelength infrared detector with improved quantum efficiency. By placing a barrier layer 103 between the bottom contact layer 102 and the absorption layer 104, and adjusting the thickness of the barrier layer 103 to differ from the other InAs layers, lattice mismatch is minimized, reducing the valence band offset between the bottom contact layer 102, barrier layer 103, absorption layer 104, and top contact layer, thus reducing dark current noise and improving the quantum efficiency of the detection device. By adjusting the thickness of the InAs layer in the M-type superlattice structure, the cutoff wavelength of the absorption layer 104 is varied while maintaining a substantially unchanged valence band position. This allows for the design of a series of long-wavelength detectors capable of detecting wavelengths from 8 μm to 12 μm. The resulting M-type superlattice (MSL) maintains a substantially unchanged valence band position, ensuring a large conduction band offset (CBO) between the two materials, a sufficiently high electron barrier, and a small and controllable valence band offset (VBO) within 10 meV, thereby suppressing dark current.

[0058] The long-wave infrared detector with improved quantum efficiency provided in the embodiments of the present invention is prepared by the following method:

[0059] First, the layered structure is grown by molecular beam epitaxy: a buffer layer 101 of heavily n-type doped GaSb, a bottom contact layer 102 of n-type doped InAs / GaSb / AlSb / GaSb superlattice material, a barrier layer 103 of unintentionally doped InAs / GaSb / AlSb / GaSb superlattice material, an absorption layer 104 of weakly n-type doped InAs / GaSb / AlSb / GaSb superlattice material, a top contact layer 105 of n-type doped InAs / GaSb / AlSb / GaSb superlattice material, and a capping layer 106 of heavily n-type doped InAs are sequentially grown on a Te-doped GaSb(100) substrate 100. The Te-doped GaSb(100) substrate 100 can be prepared by Czochralski method, Bridgman method, vertical gradient solidification method, and moving heater method.

[0060] Secondly, an etching process is performed on the material sample after growth: the etched pattern is transferred to the sample through photolithography, exposure, development and other processes, and then the thickness of the capping layer 106, the top contact layer 105, the barrier layer 103 and the absorption layer 104 are etched, all the way down to the buffer layer 101.

[0061] Then, after etching, ohmic contact electrodes are prepared: the photoresist is cleaned off, and then the patterns of the first electrode 300 and the second electrode 301 are transferred onto the sample through photolithography, exposure, development and other processes. Electrode materials, including but not limited to Ti, Pt, Au, Cu, Ni, etc., are deposited by vapor deposition.

[0062] Finally, after electrode fabrication, a passivation process is performed: the photoresist is cleaned off, and then the passivation layer pattern is transferred onto the sample through photolithography, exposure, and development. A first passivation layer 200 and a second passivation layer 201, each 200-500 nm thick, are grown on the mesa structure, containing SiO2 or SiN. x .

[0063] Figure 2 The images show the subband dispersion patterns of the absorption layer 104 at 77 K for different InAs thicknesses in the M-type superlattice. Figure 2 (a) The number of InAs / GaSb / AlSb / GaSb periodic layers in the absorption layer 104 is 11 / 4 / 1 / 4MLs; Figure 2 (b) The number of InAs / GaSb / AlSb / GaSb periodic layers in the absorption layer 104 is 11.5 / 4 / 1 / 4MLs; Figure 2 (c) The number of InAs / GaSb / AlSb / GaSb periodic layers in the absorption layer 104 is 12 / 4 / 1 / 4MLs; Figure 2 (d) The number of InAs / GaSb / AlSb / GaSb periodic layers in the absorption layer 104 is 12.5 / 4 / 1 / 4 MLs. Among them, Figure 2 The horizontal axis represents wavenumber, and the vertical axis represents energy level.

[0064] Figure 3 The graph shows the absorption coefficient curves of the 104 absorption layer at 77K for different InAs thicknesses in the M-type superlattice. Figure 3 (a) The number of InAs / GaSb / AlSb / GaSb periodic layers in the absorption layer 104 is 11 / 4 / 1 / 4MLs; Figure 3 (b) The number of InAs / GaSb / AlSb / GaSb periodic layers in the absorption layer 104 is 11.5 / 4 / 1 / 4MLs; Figure 3 (c) The number of InAs / GaSb / AlSb / GaSb periodic layers in the absorption layer 104 is 12 / 4 / 1 / 4MLs; Figure 3In (d), the InAs / GaSb / AlSb / GaSb periodicity of the absorption layer 104 is 12.5 / 4 / 1 / 4 MLs. It can be seen that the cutoff wavelengths for the four different periodicity structures are 11 μm, 12 μm, 12.6 μm, and 13.6 μm, respectively. The band gap E... g The correspondence between E and the cutoff wavelength λ is E g =1.24 / λ(eV), Figure 2 and Figure 3 The results can correspond to each other. Figure 3 The horizontal axis represents wavelength, and the vertical axis represents absorption coefficient.

[0065] like Figure 4 The diagram shows the band structure of a long-wave infrared detector under a 0V bias voltage. Among them, Figure 4 (a) is the band structure curve of the InAs / GaSb / AlSb / GaSb periodic layer number of M-type superlattice with 11 / 4 / 1 / 4MLs. Figure 4 (b) shows the band structure curves of the InAs / GaSb / AlSb / GaSb M-type superlattice with 12 / 4 / 1 / 4MLs periodicity layers. The horizontal axis represents the positions of different M-type superlattice layers, from left to right: bottom contact layer 102, barrier layer 103, absorption layer 104, and top contact layer 105. The vertical axis represents the conduction band CB, valence band VB, and electron Fermi level F. C Hole Fermi level F V The energy level values ​​of the curve.

[0066] Figure 5 for Figure 4 Quantum efficiency corresponding to two types of long-wave infrared detectors Figure 5 (a) is a quantum efficiency curve of InAs / GaSb / AlSb / GaSb periodic layers of M-type superlattice with 11 / 4 / 1 / 4MLs; Figure 5 (b) is a quantum efficiency curve of InAs / GaSb / AlSb / GaSb with 12 / 4 / 1 / 4MLs periodic layers in M-type superlattice. It can be seen that the quantum efficiency at the peak can reach about 21% and 19%, respectively.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A long-wavelength infrared detector with improved quantum efficiency, characterized in that, include: Bottom contact layer; A barrier layer, the barrier layer extending over the bottom contact layer; An absorption layer is extended over the barrier layer; A top contact layer extending beyond the absorbent layer; The bottom contact layer, the barrier layer, the absorption layer, and the top contact layer are all M-type superlattices of InAs / GaSb / AlSb / GaSb. The InAs layer of the barrier layer has a different thickness than that of the bottom contact layer, the absorption layer, and the top contact layer, while the GaSb / AlSb / GaSb layer has the same thickness. The superlattice material of the absorption layer has a cutoff wavelength corresponding to the long-wave infrared band of 8 μm to 12 μm and a thickness of 1-3 micrometers; the superlattice material of the barrier layer has a cutoff wavelength in the mid-wave infrared band and a thickness of less than 500 nanometers; the barrier layer is unintentionally doped, exhibiting weak p-type doping, with a doping concentration of 1×10⁻⁶. 15 -1×10 16 cm -3 The absorption layer is weakly n-type doped with a doping concentration of 5 × 10⁻⁶. 15 -5×10 16 cm -3 .

2. The long-wavelength infrared detector with improved quantum efficiency according to claim 1, characterized in that, Also includes: Substrate layer; A buffer layer is epitaxially mounted on the substrate layer, and a bottom contact layer is epitaxially mounted on the buffer layer. The doping concentration of the buffer layer is greater than 1 × 10⁻⁶. 18 cm -3 , used to prepare ohmic contacts; A capping layer, extending beyond the top contact layer, has a doping concentration greater than 1 × 10⁻⁶. 18 cm -3 , used to prepare ohmic contacts.

3. The long-wavelength infrared detector with improved quantum efficiency according to claim 1, characterized in that, The cutoff wavelength of the superlattice material in the bottom contact layer and the top contact layer is the same as that in the absorption layer, and the thickness is less than 1 micrometer.

4. The long-wavelength infrared detector with improved quantum efficiency according to claim 2, characterized in that, The bottom contact layer and the top contact layer are n-type doped with a doping concentration of 1×10⁻⁶. 17 -1×10 18 cm -3 .

5. The long-wavelength infrared detector with improved quantum efficiency according to claim 1, characterized in that, The conduction band vacuum level of the barrier layer is more than 150 meV higher than the conduction band vacuum level of the absorption layer, and the difference between the valence band vacuum level of the barrier layer and the valence band vacuum level of the absorption layer is less than 10 meV.

6. The long-wavelength infrared detector with improved quantum efficiency according to claim 5, characterized in that, The band gap of the barrier layer is more than 170 meV higher than that of the absorption layer.

7. The long-wavelength infrared detector with improved quantum efficiency according to claim 2, characterized in that, Also includes: The first passivation layer is disposed on the outermost periphery above the buffer layer and is in the form of an annular protrusion. The second passivation layer is disposed above the buffer layer and surrounds the outermost periphery of the bottom contact layer, the absorption layer, the barrier layer, the top contact layer and part of the capping layer; The first electrode is disposed above the buffer layer and adjacent to the first passivation layer and the second passivation layer; The second electrode is disposed above the capping layer and adjacent to the inner side of the second passivation layer, and is in the form of an annular protrusion.

Images