Two-color infrared detector

Abstract

A GaSb substrate, a GaSb buffer layer, an epitaxial thin film, a first electrode and a second electrode are adopted, the GaSb substrate, the GaSb buffer layer and the epitaxial thin film are sequentially stacked, and the epitaxial thin film comprises a first contact layer, a long wave absorption layer, a medium wave absorption layer and a second contact layer which are sequentially stacked; the first contact layer is in contact with the GaSb buffer layer; and etching is carried out on the basis of the epitaxial thin film to form a step, the depth of the step reaches the first contact layer, the first electrode is conducted with the first contact layer, the second electrode is conducted with the second contact layer, finally, a two-color infrared detector structure is formed, 12ML InAs / 2ML InAs0. 5Sb0. 5 superlattice is used as a material of the medium-wave absorption layer, good lattice matching is formed between the medium-wave absorption layer and the long-wave absorption layer, and the performance of the two-color infrared detector is improved. Therefore, interface defects and stress accumulation caused by lattice mismatch are reduced, and a smooth and uniform interface is provided for subsequent growth of the epitaxial layer, so that the growth difficulty of the epitaxial layer can be reduced.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor technology, and specifically relates to a dual-color infrared detector. Background Art

[0002] Antimonide type II superlattice has become one of the preferred materials for infrared detectors due to its mature growth technology, high quantum efficiency and flexible band control. Existing infrared detectors often use superlattice materials such as InAs / InAsSb or InAs / GaSb, among which InAs / InAsSb materials are mainly used in medium and long-wave infrared optoelectronic devices.

[0003] In the related art, the dual-color infrared detector mainly uses the long-wave absorption region of 28ML InAs / 7ML InAsSb and the medium-wave absorption region of 6MLInAs / 7ML InAsSb as the long-wave and medium-wave channels of the dual-color infrared detector.

[0004] However, using 6ML InAs / 7ML InAsSb as the medium-wave absorption layer will cause the problem of greater difficulty in growing the epitaxial layer. Summary of the invention

[0005] The present application aims to provide a two-color infrared detector capable of solving the problem of difficulty in epitaxial growth of a medium-wave absorption layer in related technologies.

[0006] In order to solve the above technical problems, this application is implemented as follows:

[0007] The embodiment of the present application proposes a two-color infrared detector, comprising: a GaSb substrate, a GaSb buffer layer, an epitaxial film, a first electrode, and a second electrode, wherein the GaSb substrate, the GaSb buffer layer, and the epitaxial film are stacked in sequence, and the epitaxial film comprises a first contact layer, a long-wave absorption layer, a medium-wave absorption layer, and a second contact layer stacked in sequence; the first contact layer is in contact with the GaSb buffer layer; etching is performed based on the epitaxial film to form a step, the depth of the step reaches the first contact layer, the first electrode is conductive with the first contact layer, and the second electrode is conductive with the second contact layer;

[0008] The medium wave absorption layer includes 12ML InAs / 2ML InAs stacked in sequence. 0.5 Sb 0.5 Superlattice materials.

[0009] Optionally, the long-wave absorption layer comprises 28ML InAs / 7ML InAs stacked in sequence. 0.5 Sb 0.5 Superlattice.

[0010] Optionally, the thickness of the long-wave absorption layer is 1800-2200 nm.

[0011] Optionally, the epitaxial film further includes a barrier layer, and the barrier layer is arranged between the medium-wave absorption layer and the long-wave absorption layer.

[0012] Optionally, the thickness of the barrier layer is 150 nm to 250 nm, and the material of the barrier layer is AlAsSb alloy.

[0013] Optionally, the epitaxial film further includes a capping layer stacked on a surface of the second contact layer, and the second electrode is in contact with the capping layer.

[0014] Optionally, the thickness of the first contact layer is 300-600 nm, and the material of the first contact layer is Si-doped InAs / InAs 0.5 Sb 0.5 Superlattice.

[0015] Optionally, the doping concentration of Si in the first contact layer is 5×10 17 cm -3 ~2×10 18 cm -3 .

[0016] Optionally, the thickness of the second contact layer is 250nm-350nm, and the material of the second contact layer is Be-doped InAs / InAs 0.5 Sb 0.5 Superlattice.

[0017] Optionally, the doping concentration of Be in the second contact layer is 5×10 17 cm -3 ~2×10 18 cm -3 .

[0018] Optionally, the material of the cap layer is InAs alloy.

[0019] Optionally, the material of the first electrode and / or the second electrode is Ti / Pt / Au alloy.

[0020] In the embodiment of the present application, a dual-color infrared detector structure is formed by using a GaSb substrate, a GaSb buffer layer, an epitaxial film, a first electrode, and a second electrode, wherein 12ML InAs / 2ML InAs 0.5 Sb 0.5 Superlattice as the material of the medium wave absorption layer, 12ML InAs / 2ML InAs 0.5 Sb 0.5A good lattice match is formed between the superlattice and the long-wave absorption layer, which reduces the interface defects and stress accumulation caused by lattice mismatch, and also provides a smooth and uniform interface for the subsequent growth of the epitaxial layer, thereby reducing the difficulty of growing the epitaxial film and solving the problem of difficulty in growing the epitaxial layer of the two-color infrared detector.

[0021] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0023] Figure 1 is a schematic structural diagram of a dual-color infrared detector according to an embodiment of the present application;

[0024] Figure 2 is the conduction band E of each InAs / InAsSb superlattice in the dual-color infrared detector according to the embodiment of the present application C and valence band E V Relative position comparison diagram;

[0025] Figure 3 Schematic diagram of the energy bands of a dual-color infrared detector according to an embodiment of the present application.

[0026] Reference numerals:

[0027] 10-GaSb substrate, 20-GaSb buffer layer, 30-epitaxial thin film, 31-first contact layer, 32-long wave absorption layer, 33-barrier layer, 34-medium wave absorption layer, 35-second contact layer, 36-cap layer, 40-second electrode, 41-first electrode. DETAILED DESCRIPTION

[0028] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0029] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0030] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0031] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0032] A dual-color infrared detector provided in an embodiment of the present application is described in detail below through specific embodiments and application scenarios in conjunction with the accompanying drawings.

[0033] A two-color infrared detector provided according to an embodiment of the present application includes: a GaSb substrate 10, a GaSb buffer layer 20, an epitaxial film 30, a first electrode 41 and a second electrode 40, wherein the GaSb substrate 10, the GaSb buffer layer 20 and the epitaxial film 30 are stacked in sequence, and the epitaxial film 30 includes a first contact layer 31, a long-wave absorption layer 32, a medium-wave absorption layer 34, and a second contact layer 35 stacked in sequence; the first contact layer 31 is in contact with the GaSb buffer layer 20; etching is performed on the basis of the epitaxial film 30 to form a step, the depth of the step reaches the first contact layer 31, the first electrode 41 is conductive with the first contact layer 31, and the second electrode 40 is conductive with the second contact layer 35;

[0034] The medium wave absorption layer 34 includes 12ML InAs / 2ML InAs stacked in sequence. 0.5 Sb 0.5Superlattice material. ML (monolayer) refers to a single atomic layer. InAs material has 12 single atomic layers. 0.5 Sb 0.5 The material is 2 monoatomic layers, 0.5 refers to the InAs and Sb in InAs 0.5 Sb 0.5 The components in the superlattice material are 0.5. 12 monoatomic layers of InAs material and 2 monoatomic layers of InAs 0.5 Sb 0.5 The materials are stacked in sequence and grown periodically as a unit to form the medium-wave absorption layer 34. InAs can be stacked and grown on the long-wave absorption layer 32 first, or InAs can be stacked and grown first. 0.5 Sb 0.5 , for InAs / InAs 0.5 Sb 0.5 The stacking direction is not limited in this embodiment.

[0035] In some embodiments, Figure 1 As shown, a dual-color infrared detector structure is formed by using a GaSb substrate 10, a GaSb buffer layer 20, an epitaxial film 30, a first electrode 41, and a second electrode 40. The GaSb buffer layer 20 is disposed on the GaSb substrate, and an epitaxial film 30 is grown on the GaSb buffer layer 20, wherein the epitaxial film 30 comprises a first contact layer 31, a long-wave absorption layer 32, a medium-wave absorption layer 34, and a second contact layer 35 from bottom to top; the epitaxial film 30 is etched to form a step, and the step etching depth reaches the first contact layer 31, a groove is made, and a first electrode 41 is deposited on the groove, and the first electrode 41 forms a good ohmic contact with the first contact layer 31 to achieve electrical connection, and a second electrode 40 is deposited on the table, and the second electrode 40 forms a good ohmic contact with the second contact layer 35 to achieve electrical connection, so that the current can pass smoothly. In addition, the first electrode 41 and the second electrode 40 cover the surface of the epitaxial film 30, which can prevent the epitaxial film 30 from being corroded by the external environment, such as oxygen, moisture, etc., thereby extending the service life of the infrared detector.

[0036] During the epitaxial growth process, due to the difference in lattice constants between different materials, lattice mismatch may occur. The GaSb substrate 10 is the basis for the growth of the epitaxial film 30. The lattice matching degree between the GaSb material and the epitaxial film 30 is high, which can reduce the generation of lattice mismatch and defects, and provide a stable crystal structure foundation for the subsequent growth of the GaSb buffer layer 20 and the epitaxial film 30 on the GaSb substrate 10, thereby reducing the difficulty of epitaxial growth; in addition, the GaSb substrate 10 is a narrow-bandwidth semiconductor material, which can optimize the conductivity and carrier mobility of the two-color infrared detector, thereby improving the overall performance of the two-color infrared detector.

[0037] The GaSb buffer layer 20 can be used as a transition layer to further reduce the degree of lattice mismatch, so that the subsequently grown epitaxial film 30 can better adapt to the GaSb substrate 10, thereby improving the crystal quality and growth uniformity of the epitaxial film 30. In addition, by controlling the growth conditions and thickness and other parameters of the GaSb buffer layer 20, the surface morphology of the epitaxial film 30 can be optimized to obtain a flatter, smoother, and more uniform epitaxial layer surface, thereby improving the optical and electrical properties of the dual-color infrared detector.

[0038] The first contact layer 31 is the main channel for current to enter the epitaxial film 30. When the two-color infrared detector is working, the current is injected into the epitaxial film 30 through the first contact layer 31, thereby driving the two-color infrared detector to work; the second contact layer 35 is the main channel for current to flow out of the epitaxial film 30. When the two-color infrared detector is working, the current is transmitted in the epitaxial film 30 and then led out to the external circuit through the second contact layer 35. In addition, the first contact layer 31 is the substrate of the epitaxial film 30, which can provide strong structural support for the epitaxial film 30 and improve the integrity and stability of the epitaxial film 30 in the subsequent processing process.

[0039] Figure 2 is the conduction band E of InAs / InAsSb superlattice C and valence band E V The relative position comparison diagram of the middle wave absorption layer 34 is shown in FIG. 1 , wherein the horizontal axis is the thickness of the middle wave absorption layer 34, Ec is the conduction band step, Ev is the valence band step, InAs material and InAs 0.5 Sb 0.5 The materials are stacked in sequence to form a whole and grow periodically along the thickness direction to form a medium-wave absorption layer 34. InAs / InAs 0.5 Sb 0.5 The conduction band bottom energy of InAs in superlattice materials is lower than that of InAs 0.5 Sb 0.5 The valence band top energy forms a "gap-type" band structure, in which electrons are confined in the InAs layer and holes are confined in the InAs layer. 0.5 Sb 0.5 In the layer, the change of the single atomic layer will affect the distribution of electrons and holes, thereby affecting the effective bandgap width and optoelectronic performance of the superlattice. In this embodiment, the 12ML InAs / 2ML InAs0.5Sb0.5 superlattice material is used to form a good lattice match with the long-wave absorption layer 32, which reduces the interface defects and stress accumulation caused by lattice mismatch, and also provides a smooth and uniform interface for the subsequent growth of the epitaxial layer, reducing the difficulty of the epitaxial layer growth. In addition, the 12ML InAs / 2ML InAs 0.5 Sb0.5 There is no valence band step between the medium-wave absorption layer 34 and the long-wave absorption layer 32 of the superlattice material. Figure 3 As shown, the photoelectric performance of the two-color infrared detector can be improved.

[0040] Optionally, the long-wave absorption layer comprises 28ML InAs / 7ML InAs stacked in sequence. 0.5 Sb 0.5 Superlattice.

[0041] Specifically, the long-wave absorption layer 32 contacts the first contact layer 31, and the long-wave absorption layer 32 is made of InAs / InAs 0.5 Sb 0.5 Superlattice material system, and 28ML InAs and 7ML InAs 0.5 Sb 0.5 The stack is formed into a layer, and then periodically grows to form a long-wave absorption layer 32. InAs / InAs 0.5 Sb 0.5 The superlattice not only has excellent light absorption performance, but also has high quantum efficiency, which enables the two-color infrared detector to effectively absorb more incident photons and convert them into electrical signals during the detection process, thereby improving the sensitivity and signal-to-noise ratio of the two-color infrared detector. In addition, InAs / InAs 0.5 Sb 0.5 The superlattice has a large effective mass of electrons, which can suppress the tunneling effect and reduce the generation of dark current, thereby improving the detection performance of the two-color infrared detector. It should also be noted that the long-wave absorption layer 32 is made of 28ML InAs / 7ML InAs 0.5 Sb 0.5 12ML InAs / 2ML InAs of superlattice material and medium wave absorption layer 34 0.5 Sb 0.5 The superlattices match each other, which can effectively reduce the difficulty of growing the epitaxial thin film 30 .

[0042] Optionally, the thickness of the long-wave absorption layer is 1800-2200 nm.

[0043] The thickness of the long-wave absorption layer 32 is 1800 to 2200 nm. By setting the thickness of the long-wave absorption layer 32 to between 1800 and 2200 nm, a suitable thickness of the long-wave absorption layer 32 can provide the absorption layer with a longer optical path, so that more photons are absorbed and converted into carriers inside the long-wave absorption layer 32, thereby enhancing the absorption capacity of long-wave photons and improving the absorption efficiency, thereby improving the response speed and sensitivity of the two-color infrared detector. However, when the thickness of the long-wave absorption layer 32 exceeds 2200nm, on the one hand, since the photons have been mainly absorbed by the long-wave absorption layer 32 on the surface, the deep long-wave absorption layer 32 has limited contribution to the absorption of photons, resulting in a gradual slowdown in the improvement of the absorption efficiency of the long-wave absorption layer 32; on the other hand, the photogenerated carriers in the deep layer of the long-wave absorption layer 32 may experience more scattering and recombination losses during the transport process, resulting in the spectral response range moving toward the short-wave direction, affecting the spectral response range, thereby reducing the sensitivity of the two-color infrared detector. At the same time, an overly thick long-wave absorption layer 32 will increase the transmission distance and time of the carriers, thereby reducing the response speed of the two-color infrared detector. It should also be noted that an overly thick long-wave absorption layer 32 requires a longer growth process, and during the long growth process, there may be the influence of uncertain factors such as impurity contamination and temperature fluctuations, thereby affecting the growth difficulty, uniformity and quality of the material.

[0044] When the thickness of the long-wave absorption layer 32 is less than 1800nm, the absorption layer is not thick enough and will not be able to fully absorb the incident long-wave light, resulting in a large number of photons penetrating the absorption layer without being utilized, thereby reducing the photoelectric conversion efficiency of the two-color infrared detector; and, due to the insufficient thickness of the absorption layer, the number of absorbed photons is reduced, so the number of photogenerated carriers generated will also be reduced accordingly. This will cause the output signal of the two-color infrared detector to weaken, affecting its detection capability under weak light conditions. Insufficient absorption layer thickness will also cause signal weakening, and the detection limit of the two-color infrared detector will increase accordingly, thereby reducing the sensitivity of the two-color infrared detector.

[0045] For example, the thickness of the long-wave absorption layer 32 can be set to any value such as 1800 nm, 1900 nm, 2000 nm, 2100 nm, 2200 nm, or a range between any two values.

[0046] Optionally, the epitaxial film further includes a barrier layer, and the barrier layer is arranged between the medium-wave absorption layer and the long-wave absorption layer.

[0047] The epitaxial film 30 also includes a barrier layer 33, which is arranged between the medium-wave absorption layer 34 and the long-wave absorption layer 32. The main function of the barrier layer 33 is to form an energy barrier, which inhibits the flow of electrons and holes injected from the first electrode 41 between different layers, reduces the generation of dark current, and thus improves the sensitivity and detection accuracy of the two-color infrared detector. In addition, the interface effect between the barrier layer 33 and the medium-wave absorption layer 34 and the long-wave absorption layer 32, as well as the characteristics of the barrier layer 33 itself, help to enhance the response capability of the two-color infrared detector to infrared radiation and improve the detection efficiency, which enables the two-color infrared detector to achieve efficient detection within a wider wavelength range and enhance the detection capability of weak infrared signals. It should also be noted that the barrier layer 33 can also reduce the recombination and scattering process of carriers inside the two-color infrared detector, reduce the generation of noise, and improve the stability of the two-color infrared detector.

[0048] Optionally, the thickness of the barrier layer is 150 nm to 250 nm, and the material of the barrier layer is AlAsSb alloy.

[0049] The thickness of the barrier layer 33 is 150nm to 250nm, and the material of the barrier layer 33 is AlAsSb alloy. By setting the thickness of the barrier layer 33 to between 150nm and 250nm, it is possible to reduce the dark current while maintaining a high photocurrent, thereby improving the signal-to-noise ratio and other performances of the two-color infrared detector. It is understandable that when the thickness of the barrier layer 33 exceeds 250nm, the overly thick barrier layer 33 will not only absorb or block more incident infrared light, resulting in a reduction in the generation of photogenerated carriers, thereby reducing the photocurrent and responsivity of the detector, but also increase the stress inside the two-color infrared detector, affecting the stability and reliability of the device. When the thickness of the barrier layer 33 is less than 150nm, electrons or holes are more likely to cross the barrier, resulting in an increase in the leakage current (dark current) of the device under no light conditions, reducing the signal-to-noise ratio of the detector, thereby affecting the detection precision and accuracy of the two-color infrared detector. In addition, an overly thin barrier layer 33 may increase the sensitivity of the device to environmental factors such as temperature and humidity, resulting in unstable detector performance.

[0050] For example, the thickness of the barrier layer 33 can be set to any value such as 150 nm, 170 nm, 180 nm, 200 nm, 210 nm, 230 nm, 250 nm, or a range between any two values.

[0051] The material of the barrier layer 33 is AlAsSb alloy. AlAsSb alloy is used as the material of the barrier layer 33. The band gap of AlAsSb alloy is relatively wide, which can enhance the blocking effect of the AlAsSb alloy barrier layer 33 on electrons and holes, and help reduce the dark current of the two-color infrared detector under no light conditions. Lower dark current can improve the signal-to-noise ratio and detection sensitivity of the device; the band gap width of the AlAsSb alloy can be controlled by adjusting the composition of Sb, so as to achieve a good match with the medium-wave absorption layer 34 and the long-wave absorption layer 32. This match helps to reduce carrier recombination and leakage at the interface, and will also correspondingly improve the detection efficiency of the two-color infrared detector; in addition, the AlAsSb alloy has good chemical stability and thermal stability, can maintain the stability of its physical and chemical properties under high temperature or harsh environment, and can improve the reliability and life of the infrared detector under high temperature or long-term working conditions.

[0052] Optionally, the epitaxial film further includes a cap layer stacked on the surface of the second contact layer, and the second electrode is in contact with the cap layer, that is, the second electrode is conductively connected to the epitaxial film through the cap layer.

[0053] The epitaxial film 30 also includes a cap layer 36 stacked on the surface of the second contact layer 35, and the second electrode 40 is in contact with the cap layer 36. The cap layer 36 is also called a barrier layer or a covering layer. The cap layer 36 can effectively protect the second contact layer 35 below from the influence of the external environment, such as oxygen, moisture, dust and chemical corrosion. This protective effect helps to extend the service life and stability of the two-color infrared detector. In addition, the cap layer 36 can optimize the performance of the two-color infrared detector through its specific electrical, optical or thermal properties. For example, by adjusting the material and structure of the cap layer 36, the injection efficiency of carriers can be controlled, non-radiative recombination and leakage can be reduced, thereby improving the luminous efficiency, photoelectric conversion efficiency or switching speed of the two-color infrared detector.

[0054] Optionally, the thickness of the first contact layer is 300-600 nm, and the material of the first contact layer is Si-doped InAs / InAs 0.5 Sb 0.5 Superlattice.

[0055] The thickness of the first contact layer 31 is 300 to 600 nm. By setting the thickness of the first contact layer 31 to between 300 and 600 nm, it is not only helpful to reduce the lattice mismatch and defect problems at the interface between the first contact layer 31 and the GaSb buffer layer 20, and reduce the residual stress in the epitaxial film 30, thereby improving the quality of the epitaxial film 30; but also, it can optimize the carrier transmission characteristics and improve the conductivity and reliability of the two-color infrared detector.

[0056] However, when the thickness of the first contact layer 31 exceeds 600nm, the difference in thermal expansion coefficients between the first contact layer 31 and the long-wave absorption layer 32 and the GaSb buffer layer 20 may cause greater thermal stress when the temperature changes, thereby affecting the stability and reliability of the epitaxial film 30; in addition, an excessively thick first contact layer 31 may also increase the scattering and recombination of electrons or holes during the transmission process, thereby reducing the electrical performance of the dual-color infrared detector.

[0057] When the thickness of the first contact layer 31 is less than 300 nm, the thinner first contact layer 31 cannot provide sufficient support for the epitaxial film 30, resulting in a decrease in the mechanical strength of the epitaxial film 30, which is prone to cracking or damage during subsequent processing and handling. In addition, the thin first contact layer 31 may not be able to effectively block the leakage of current at the edge or defect of the epitaxial film 30, resulting in an increase in leakage current, thereby affecting the electrical performance and reliability of the dual-color infrared detector.

[0058] For example, the thickness of the first contact layer 31 can be set to any value such as 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, or a range between any two values.

[0059] The material of the first contact layer 31 is Si-doped InAs / InAs 0.5 Sb 0.5 Superlattice, InAs / InAs 0.5 Sb 0.5 The superlattice can form a good lattice match with the upper long-wave absorption layer 32, reduce interface defects and stress accumulation, and provide a smooth and uniform interface, thereby improving the performance and stability of the two-color infrared detector. 0.5 Sb 0.5 The superlattice has a high electron mobility, which enables electrons to be transmitted quickly and reduces the transmission time, thereby improving the detection efficiency and response speed of the two-color infrared detector. In some embodiments, the first contact layer 31 can be 28ML InAs / 7ML InAs 0.5 Sb 0.5 Specifically, the first contact layer 31 is composed of 28 monoatomic layers of InAs and 7 monoatomic layers of InAs 0.5 Sb 0.5 Stacked.

[0060] Si is an n-type dopant in InAs / InAs 0.5 Sb 0.5 Introducing Si doping into the superlattice can increase the InAs / InAs 0.5 Sb 0.5 The electron concentration in the superlattice increases the InAs / InAs0.5 Sb 0.5 Electrical properties of superlattice materials such as conductivity, carrier concentration and mobility.

[0061] Optionally, the doping concentration of Si in the first contact layer is 5×10 17 cm -3 ~2×10 18 cm -3 .

[0062] The doping concentration of Si in the first contact layer 31 is 5×10 17 cm -3 ~2×10 18 cm -3 By setting the doping concentration of Si in the first contact layer 31 to 5×10 17 cm -3 ~2×10 18 cm -3 , which can significantly improve the conductivity of the epitaxial film 30 and the mobility of carriers in the epitaxial film 30, thereby improving the stability and reliability of the two-color infrared detector. However, when the doping concentration of Si is too high, more impurity scattering centers will be introduced into the first contact layer 31. The presence of impurity atoms will interfere with the movement path of carriers, increase the collision frequency of carriers, and cause the mobility of carriers in the epitaxial film 30 to decrease, thereby reducing the conductivity of the first contact layer 31. In addition, the excessive introduction of impurity Si atoms will also destroy the periodic structure of epitaxial growth, increase lattice distortion and defect density, and thus affect the overall performance of the epitaxial film 30. When the doping concentration of Si is too low, the concentration of carriers cannot meet the conductivity requirements of the two-color infrared detector, thereby affecting the overall performance of the two-color infrared detector.

[0063] For example, the doping concentration of Si in the first contact layer 31 can be set to: 5×10 17 cm -3 , 6×10 17 cm -3 ,7×10 17 cm -3 ,9×10 17 cm -3 , 1×10 18 cm -3 , 2×10 18 cm -3 Any value or a range between any two values.

[0064] Optionally, the thickness of the second contact layer is 250nm-350nm, and the material of the second contact layer is Be-doped InAs / InAs 0.5 Sb 0.5 Superlattice.

[0065] The thickness of the second contact layer 35 is 250nm to 350nm. By setting the thickness of the second contact layer 35 to between 250nm and 350nm, not only can the contact resistance be minimized, the current transmission efficiency be improved, thereby improving the sensitivity and response speed of the two-color infrared detector, but also the optical efficiency and selectivity of the detector can be improved by improving the transmittance of the two-color infrared detector to infrared radiation. However, when the thickness of the second contact layer 35 exceeds 350nm, on the one hand, the contact resistance will increase, affecting the current transmission efficiency, thereby reducing the conductive performance of the second contact layer 35, and on the other hand, the heat energy transfer efficiency of the second contact layer 35 will be reduced, thereby affecting the thermal distribution and response time of the two-color infrared detector after absorbing infrared radiation. When the thickness of the second contact layer 35 is less than 250nm, the contact resistance of the second contact layer 35 will be unstable, and it will be easily affected by the external environment such as temperature and humidity, thereby affecting the stability and reliability of the two-color infrared detector. In addition, the temperature of the second contact layer 35 will change too quickly after absorbing infrared radiation, thereby affecting the response speed and stability of the two-color infrared detector.

[0066] For example, the thickness of the second contact layer 35 can be set to any value such as 250 nm, 270 nm, 300 nm, 320 nm, 350 nm, or a range between any two values.

[0067] The material of the second contact layer 35 is Be-doped InAs / InAs 0.5 Sb 0.5 The material system of the second contact layer 35 is the same as that of the first contact layer 31, and will not be described in detail here. It should be understood that InAs / InAs 0.5 Sb 0.5 The superlattice as the material of the second contact layer 35 has a better application effect on the dual-color infrared detector. In some embodiments, the second contact layer 35 can be 12MLInAs / 2ML InAs 0.5 Sb 0.5 Specifically, the second contact layer 35 is composed of 12 monoatomic layers of InAs and 2 monoatomic layers of InAs 0.5 Sb 0.5 Stacked.

[0068] Be is a P-type dopant. 0.5 Sb 0.5 Introducing Be doping into the superlattice can increase the InAs / InAs 0.5 Sb 0.5 The hole concentration in the superlattice is increased, thereby improving the conductivity and transmission efficiency of the second contact layer 35.

[0069] Optionally, the doping concentration of Be in the second contact layer is 5×10 17 cm -3 ~2×10 18 cm -3 .

[0070] The doping concentration of Be in the second contact layer 35 is 5×10 17 cm -3 ~2×10 18 cm -3 By setting the doping concentration of Be in the second contact layer 35 to 5×10 17 cm -3 ~2×10 18 cm -3 , which can effectively increase the hole concentration of the epitaxial film 30 while maintaining a high hole mobility, thereby enhancing the conductive performance of the second contact layer 35, making the current transmission smoother and the response speed faster; in addition, the appropriate Be doping concentration can reduce the specific on-resistance of the epitaxial film 30. The specific on-resistance is the ratio of the resistance to the area of ​​the device in the on state. Reducing the specific on-resistance means that under the same operating current, the voltage drop across the device will be reduced, thereby reducing the power consumption of the device and improving the energy efficiency of the device.

[0071] However, although high concentration of Be doping can further increase the hole concentration, too high doping concentration will lead to enhanced scattering between carriers and decreased mobility. In addition, high concentration doping may also cause lattice distortion, increased defects, increased stress and other problems inside the second contact layer 35, resulting in increased resistivity of the second contact layer 35, decreased conductivity, and reduced stability and reliability. When the doping concentration of Be is low, sufficient p-type carriers (holes) cannot be effectively formed in the epitaxial film 30, resulting in an insignificant improvement in the conductivity of the second contact layer 35, and the original conductivity type (such as n-type or weak conductivity) may even be maintained.

[0072] For example, the doping concentration of Be in the second contact layer 35 can be set to: 5×10 17 cm -3 , 6×10 17 cm -3 ,7×10 17 cm -3 ,9×10 17 cm -3 , 1×10 18 cm -3 , 2×10 18 cm -3 Any value or a range between any two values.

[0073] Optionally, the material of the cap layer is InAs alloy.

[0074] The material of the cap layer 36 is InAs alloy. InAs alloy has specific optical properties, such as light absorption and light emission properties. InAs alloy can adjust and optimize the enhanced light absorption efficiency of the epitaxial film 30, improve the light emission intensity, and can effectively block or filter unnecessary infrared radiation, thereby improving the selectivity and sensitivity of the two-color infrared detector; in addition, the lattice constant of the InAs cap layer 36 is similar to the lattice constant of the thin film layers such as the GaSb substrate 10 and the GaSb buffer layer 20 in the epitaxial film 30, which can achieve better lattice matching, reduce interface defects, reduce stress accumulation and scattering losses, smooth the surface morphology of the epitaxial film 30, and reduce the surface roughness, thereby improving the quality and performance of the epitaxial film 30.

[0075] Optionally, the material of the first electrode and / or the second electrode is Ti / Pt / Au alloy.

[0076] The material of the first electrode 41 and / or the second electrode 40 is Ti / Pt / Au alloy. On the one hand, the Ti / Pt / Au alloy combination can effectively form an ohmic contact, and the current can smoothly pass through the contact interface to achieve efficient current transmission. Specifically, Au, as the top layer material, has good conductivity and can ensure efficient current transmission of the electrode. Pt and Ti, as the middle layer, can further improve the contact interface and reduce the contact resistance. In addition, at high temperatures, mutual diffusion may occur between different metals, resulting in a decrease in contact performance. When the temperature is lower than 480°C, the Pt layer can effectively block the diffusion of Au, and when the temperature reaches 580°C, the diffusion of Pt and Ti becomes obvious. This characteristic helps the first electrode 41 and the second electrode 40 to maintain electrical properties and long-term stability within a relatively high temperature range.

[0077] On the other hand, the Ti / Pt / Au alloy has good adhesion to the epitaxial film 30, which enables the first electrode 41 and the second electrode 40 to be firmly attached to the epitaxial film 30, reducing the probability of the first electrode 41 and the second electrode 40 falling off, thereby improving the reliability of the two-color infrared detector.

[0078] In an embodiment of the present application, a GaSb substrate, a GaSb buffer layer, an epitaxial film, a first electrode and a second electrode are adopted, and the GaSb substrate, the GaSb buffer layer and the epitaxial film are sequentially stacked, and the epitaxial film includes a first contact layer, a long-wave absorption layer, a medium-wave absorption layer, and a second contact layer stacked in sequence; the first contact layer is in contact with the GaSb buffer layer; etching is performed on the basis of the epitaxial film to form a step, the depth of the step is to the first contact layer, the first electrode is connected to the first contact layer, and the second electrode is connected to the second contact layer, and finally a dual-color infrared detector structure is formed, wherein a 12ML InAs / 2ML InAs0.5Sb0.5 superlattice is used as a material for the medium-wave absorption layer, and a 12ML InAs / 2ML InAs 0.5 Sb 0.5 A good lattice match is formed between the superlattice and the long-wave absorption layer, which reduces the interface defects and stress accumulation caused by lattice mismatch, and also provides a smooth and uniform interface for the subsequent growth of the epitaxial layer, thereby reducing the difficulty of growing the epitaxial film and solving the problem of difficulty in growing the epitaxial layer of the two-color infrared detector.

[0079] The embodiments of the present application are described above in conjunction with the accompanying drawings. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0080] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A two-color infrared detector, characterized in that: include: GaSb substrate, GaSb buffer layer, epitaxial film, first electrode and second electrode, the GaSb substrate, GaSb buffer layer and epitaxial film are stacked in sequence, the epitaxial film comprises a first contact layer, a long-wave absorption layer, a medium-wave absorption layer and a second contact layer stacked in sequence; the first contact layer is in contact with the GaSb buffer layer; etching is performed based on the epitaxial film to form a step, the depth of the step reaches the first contact layer, the first electrode is conductive with the first contact layer, and the second electrode is conductive with the second contact layer; The medium wave absorption layer includes 12ML InAs / 2ML InAs stacked in sequence. 0.5 Sb 0.5 Superlattice materials.

2. The two-color infrared detector according to claim 1, characterized in that: The long-wave absorption layer includes 28MLInAs / 7MLInAs stacked in sequence. 0.5 Sb 0.5 Superlattice.

3. The two-color infrared detector according to claim 1, characterized in that: The thickness of the long-wave absorption layer is 1800-2200 nm.

4. The two-color infrared detector according to claim 1, characterized in that: The epitaxial film further includes a barrier layer, and the barrier layer is arranged between the medium-wave absorption layer and the long-wave absorption layer.

5. The two-color infrared detector according to claim 4, characterized in that: The thickness of the barrier layer is 150nm-250nm, and the material of the barrier layer is AlAsSb alloy.

6. The two-color infrared detector according to any one of claims 1 to 5, characterized in that: The epitaxial film further includes a cap layer stacked on the surface of the second contact layer, and the second electrode is in contact with the cap layer.

7. The two-color infrared detector according to any one of claims 1 to 5, characterized in that: The thickness of the first contact layer is 300-600 nm, and the material of the first contact layer is Si-doped InAs / InAs 0.5 Sb 0.5 Superlattice.

8. The two-color infrared detector according to claim 7, characterized in that: The doping concentration of Si in the first contact layer is 5×10 17 cm -3 ~2×10 18 cm -3 .

9. The two-color infrared detector according to claim 1, characterized in that: The thickness of the second contact layer is 250nm-350nm, and the material of the second contact layer is Be-doped InAs / InAs 0.5 Sb 0.5 Superlattice.

10. The two-color infrared detector according to claim 9, characterized in that: The doping concentration of Be in the second contact layer is 5×10 17 cm -3 ~2×10 18 cm -3 .

11. The two-color infrared detector according to claim 1, characterized in that: The material of the cap layer is InAs alloy.

12. The two-color infrared detector according to claim 1, characterized in that: The material of the first electrode and / or the second electrode is Ti / Pt / Au alloy.

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