A three-color infrared detector based on a new gradient barrier structure

Abstract

The invention discloses a three-color infrared detector based on a novel gradient barrier structure, and relates to the field of semiconductor technology. The three-color infrared detector comprises short-wave, medium-wave and long-wave three-channel regions and a gradient barrier layer, and only an upper electrode and a lower electrode are provided. Each channel is opened or closed respectively by applying different bias voltages to the lower electrode. The absorption layer of each channel adopts InAs / GaSb superlattice and is p-type doped. InAs / AlSb gradient barriers are inserted between channels to suppress reverse carrier transport and reduce band crosstalk. The three-color infrared detector simplifies the process flow, reduces dark current and noise, improves detection performance, and is suitable for the field of multi-band infrared detection.

Description

Technical Field

[0001] The invention relates to the field of semiconductor technology, and in particular to a three-color infrared detector based on a novel gradient barrier structure. Background Art

[0002] With the increasing demand for infrared detection technology in fields such as security, environmental monitoring, and medical imaging, it is particularly important to develop high-performance infrared detectors. Three-color infrared detectors can simultaneously detect short-wave, medium-wave, and long-wave infrared radiation, which improves the flexibility and application range of the detector. At present, epitaxial growth of high crystal structure quality is a major problem facing three-color infrared detectors, which limits the performance improvement of detectors, such as quantum efficiency and dark current. In addition, another major challenge facing three-color infrared detectors is the crosstalk between signal channels in different bands, which limits the application range of the detector bias. The migration of photogenerated carriers between different channels is the main cause of the crosstalk problem. At present, most non-polar barriers such as structures such as nBn are used to alleviate it, but the complex structure often leads to poor growth quality, which puts higher requirements on the epitaxial process and device preparation process.

[0003] For example, the patent application with publication number CN115483300A discloses an nBn type gradient barrier infrared detector. and The introduction of a gradient barrier structure achieves the optimization of the valence band barrier, effectively reduces the transmission barrier of photogenerated carriers, improves the hole collection efficiency, and reduces the dark current.

[0004] However, this method still has some shortcomings. For example, it is mainly applied to monochromatic or dual-band detectors of nBn structure, and the performance optimization of multi-band detectors is not fully considered. In addition, the gradient structure of this design has high requirements on the uniformity of material growth and high process complexity, and the problem of crosstalk between signals of different bands is not solved. Summary of the invention

[0005] In view of the shortcomings of the prior art, the main purpose of the present invention is to provide a novel method based on a gradual doping concentration of ~ The device structure of the three-color infrared detector based on the InAs / AlSb barrier antimonide superlattice. By modulating the conduction band height by bias voltage, the short-wave channel and the medium-wave channel are mutually converted under different negative bias voltages, and the signal is received through the upper electrode, while the long-wave signal is collected through the lower electrode under positive bias voltage.

[0006] To achieve the above object, the present invention provides a three-color infrared detector based on a novel gradient barrier structure, comprising:

[0007] A short-wave channel region, the short-wave channel region comprising: a short-wave I region superlattice structure, including an InAs / GaSb stack, and lightly p-type doped; a short-wave P region superlattice structure, the doping concentration of which is greater than the doping concentration of the short-wave I region, and is used to provide an upper electrode ohmic contact;

[0008] The graded barrier layer is located between the short-wave channel and the medium-wave channel. The graded barrier layer includes an InAs / AlSb stack and is to Gradient n-type doping;

[0009] The medium wave channel region includes: a medium wave I region superlattice structure, which adopts an InAs / GaSb stack and is lightly p-type doped; a medium wave P region; a common contact layer, which includes a GaSb material and is heavily p-type doped, and is used to form an electron barrier between the medium wave channel and the long wave channel;

[0010] The long-wave channel region includes: a long-wave I region superlattice structure, which adopts InAs / GaSb stacking and is lightly p-type doped; an M-type barrier layer in the M region, in which an AlSb layer is inserted into the long-wave I region or adjacent to it to form an M-type barrier for inhibiting the reverse transport of holes; an N-type doped layer in the N region, which is located below the long-wave I region or the M region and is used to provide an ohmic contact with the lower electrode;

[0011] A lower electrode substrate structure, the lower electrode substrate structure comprising: a GaSb substrate; a buffer layer located on the GaSb substrate;

[0012] The three-color infrared detector is only provided with an upper electrode and a lower electrode, and bias voltages of different polarities and amplitudes are applied to the lower electrode to respectively open or close the three detection channels of short wave, medium wave and long wave.

[0013] As an optional implementation, the short-wave I region uses a 5InAs / 8GaSb superlattice stack, and the p-type light doping concentration is , thickness is 1 to 2.5 μm;

[0014] The short-wave P region is made of the same material stack as the short-wave I region and is heavily p-doped with a concentration of , with a thickness of 200nm.

[0015] As an optional implementation, the medium-wave region I adopts 9InAs / 8GaSb superlattice stacking, and the p-type light doping concentration is , thickness is 1 to 2.5 μm.

[0016] As an optional implementation, the long-wave I region uses a 12.5InAs / 7GaSb superlattice stack, and the p-type light doping concentration is , thickness is 1 to 2.5 μm;

[0017] The M region adopts a 18InAs / 3GaSb / 5AlSb / 3GaSb stacked structure with a thickness of 500nm;

[0018] The N region adopts a 18InAs / 3GaSb / 5AlSb / 3GaSb stacked structure and is n-type doped with a concentration of .

[0019] As an optional implementation, the common contact layer is made of GaSb, and the p-type doping concentration is , thickness is 500nm.

[0020] As an optional implementation manner, the InAs / AlSb superlattice period number of the graded barrier layer is 9.5 / 9 periods, and the total thickness is 150 nm.

[0021] As an optional implementation, the working modes of the three-color infrared detector when biased include:

[0022] In response to the positive bias applied to the lower electrode, the long-wave channel is turned on and the short-wave and medium-wave channels are closed;

[0023] In response to a negative bias voltage applied to the lower electrode and the bias voltage being in the range of -0.1V to -0.5V, the short wave channel is turned on, and the medium wave and long wave channels are turned off;

[0024] In response to a negative bias voltage being applied to the lower electrode and the bias voltage being less than or equal to -0.5 V, the short wave and medium wave channels are turned on, and the long wave channel is turned off.

[0025] As an optional implementation, the buffer layer is Te doped with a concentration of GaSb buffer layer with a thickness of 988nm.

[0026] As an optional implementation, the growth method of the three-color infrared detector is molecular beam epitaxy or metal organic chemical vapor deposition.

[0027] Compared with the prior art, the invention has the following beneficial effects: the traditional three-color infrared detection device needs to use the upper, middle and lower electrodes to realize the collection of three cut-off wavelength signals, while the new doped gradient InAs / AlSb barrier structure can realize the collection of three cut-off wavelength optical signals using the upper and lower electrodes. Under positive bias, the long-wave channel is turned on, and the medium-wave and short-wave channels are turned off; between -0.1V and -0.5V, the short-wave channel is turned on, and the medium-wave and long-wave channels are turned off; under negative bias less than or equal to -0.5V, the short-wave and medium-wave channels are turned on, and the long-wave channel is turned off.

[0028] The device structure design of the three-color infrared detector based on the novel gradient barrier structure disclosed in the present application reduces the overall complexity of the device. In addition, the wide-bandgap barrier can also reduce the dark current noise of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the device structure of a three-color infrared detector based on a novel gradient barrier structure provided in an embodiment of the present application;

[0030] Figure 2 A schematic diagram of the equilibrium state energy band of the three-color infrared detector provided in an embodiment of the present application;

[0031] Figure 3 A schematic diagram of the energy bands of a three-color infrared detector under different bias conditions provided in an embodiment of the present application. DETAILED DESCRIPTION

[0032] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the following embodiments are only used to illustrate some examples of the present invention, and are not intended to be all or only limitations of the present invention.

[0033] See also Figure 1 , Figure 1 A schematic diagram of the device structure of a three-color infrared detector based on a novel gradient barrier structure provided in an embodiment of the present application, wherein the meanings of the names of the layers in the figure are as follows:

[0034] GaSb sub: refers to the GaSb substrate, which is used to support the entire epitaxial structure;

[0035] GaSb Buffer: GaSb buffer layer, used to improve lattice matching with the substrate;

[0036] 18InAs / 3GaSb / 5AlSb / 3GaSb LW-N: long-wave (N region) superlattice, heavily n-type doped, used for lower electrode ohmic contact;

[0037] 18InAs / 3GaSb / 5AlSb / 3GaSb LW-M: long-wave (M region) barrier layer, AlSb is inserted into InAs / GaSb to form an M-type hole barrier;

[0038] 12.5InAs / 7GaSb LW-I: long-wave (I region) superlattice, p-type lightly doped or intrinsic state, used to absorb long-wave infrared;

[0039] 8InAs / 12GaSb LW-P: long-wave (P-zone) superlattice, heavily p-type doped, used to control the long-wave channel energy band;

[0040] GaSb Be dope: Common contact layer (GaSb material, heavily doped with Be), used to provide a barrier between the long-wave and medium-wave channels;

[0041] 9InAs / 8GaSb MW-I: medium-wave (I region) superlattice, lightly p-type doped;

[0042] 9.5InAs / 9AlSb MW-Barrier: medium-wave barrier layer, n-type gradient doping, can block majority carriers;

[0043] 5InAs / 8GaSb SW-I: short-wave (I region) superlattice, lightly p-type doped, for short-wave infrared absorption;

[0044] 5InAs / 8GaSb SW-P: short-wave (P-zone) superlattice, heavily p-type doped, used to regulate the short-wave channel energy band and hole transport and provide ohmic contact to the upper electrode;

[0045] Top electrode: deposited on the top layer to achieve electrical contact with the outside of the device;

[0046] Bottom electrode: Generally located at the substrate or N region, it realizes electrical contact with the other end of the device.

[0047] The present invention provides a three-color infrared detector based on a novel gradient barrier structure, comprising:

[0048] A short-wave channel region, the short-wave channel region comprising: a short-wave I region superlattice structure, including an InAs / GaSb stack, and lightly p-type doped; a short-wave P region superlattice structure, the doping concentration of which is greater than the doping concentration of the short-wave I region, and is used to provide an upper electrode ohmic contact;

[0049] The graded barrier layer is located between the short-wave channel and the medium-wave channel. The graded barrier layer includes an InAs / AlSb stack and is to Gradient n-type doping;

[0050] The medium wave channel region includes: a medium wave I region superlattice structure, which adopts an InAs / GaSb stack and is lightly p-type doped; a medium wave P region; a common contact layer, which includes a GaSb material and is heavily p-type doped, and is used to form an electron barrier between the medium wave channel and the long wave channel;

[0051] The long-wave channel region includes: a long-wave I region superlattice structure, which adopts InAs / GaSb stacking and is lightly p-type doped; an M-type barrier layer in the M region, in which an AlSb layer is inserted into the long-wave I region or adjacent to it to form an M-type barrier for inhibiting the reverse transport of holes; an N-type doped layer in the N region, which is located below the long-wave I region or the M region and is used to provide an ohmic contact with the lower electrode;

[0052] A lower electrode substrate structure, the lower electrode substrate structure comprising: a GaSb substrate; a buffer layer located on the GaSb substrate;

[0053] The three-color infrared detector is only provided with an upper electrode and a lower electrode, and bias voltages of different polarities and amplitudes are applied to the lower electrode to respectively open or close the three detection channels of short wave, medium wave and long wave.

[0054] It should be noted that the above-mentioned InAs / GaSb stack or InAs / GaSb superlattice refers to a multi-layer periodic structure consisting of several periods of alternately grown InAs layers and GaSb layers. The thickness of the InAs layer and GaSb layer in each period can be designed according to the required detection band, material stress matching or band gap regulation. This structure is usually grown by molecular beam epitaxy (MBE) or metal organic chemical vapor deposition (MOCVD) to form a type II superlattice, thereby achieving absorption and detection of specific infrared bands.

[0055] The epitaxial substrate is an n-type GaSb substrate in the (001) direction.

[0056] It should be noted that the short-wave channel, the medium-wave channel and the long-wave channel in the present invention correspond to detection functions in different infrared wavelength ranges respectively.

[0057] Among them, the shortwave channel is usually used to detect infrared radiation of about 2 to 3 μm (or 1 to 3 μm), because this band can be used in some near-infrared or short-wave infrared imaging and monitoring scenarios;

[0058] The medium wave channel is often used to detect infrared radiation in the range of about 3 to 5 μm. This band is widely used in security, gas detection and other fields.

[0059] The long-wave channel is mainly used to detect infrared radiation in the range of about 8 to 12 μm (or 7 to 14 μm, etc.), and is suitable for long-wave infrared applications such as thermal imaging and environmental monitoring.

[0060] The present invention forms three superlattice absorption layers of short wave, medium wave and long wave in the same device structure in sequence, and combines appropriate doping and barrier design, so that each channel can detect different infrared bands separately or simultaneously. When a channel needs to be enabled or disabled, it is only necessary to apply bias voltages of different polarities and amplitudes to the lower electrode to regulate the corresponding electron or hole transmission path, thereby realizing the multi-channel switching and independent readout functions of the three-color infrared detector.

[0061] In the specific implementation, a GaSb buffer layer (Buffer layer) with a thickness of about 988 nm is first grown on a (001) oriented n-type GaSb substrate, wherein the Te doping concentration is about Subsequently, a long-wave channel region structure with a thickness of about 3.5 μm is grown on the buffer layer. The long-wave channel region includes:

[0062] Long-wave I region superlattice structure: using a superlattice with a period of (12.5MLInAs / 7MLGaSb) to The Be doping thickness can be selected in the range of 1 to 2.5 μm to ensure effective absorption of long-wave light and controllable carrier recombination rate;

[0063] It should be noted that 12.5MLInAs / 7MLGaSb means that each period includes a 12.5ML thick InAs layer and a 7ML thick GaSb layer grown alternately. By periodically repeating this combination, the desired type II superlattice structure can be achieved for absorption and response in a specific infrared band.

[0064] It should be noted that the doping concentration of each layer of the present invention is not limited to the above typical values. or , but can be selected in and In order to balance the process feasibility and device performance. In addition, the implementation of the typical values ​​as examples below is similar and will not be repeated.

[0065] M and N regions: Several periods of (18InAs / 3GaSb / 5AlSb / 3GaSb) superlattice are inserted in the long-wave I region or adjacent to it, and the total thickness of each region is about 500nm. The Si doping is used for the ohmic contact of the lower electrode; the M region is undoped and is used to construct an M-type hole barrier to inhibit the reverse transport of holes;

[0066] It should be noted that 18InAs / 3GaSb / 5AlSb / 3GaSb means that each period of the superlattice is composed of an InAs layer of about 18ML thick, a GaSb layer of 3ML thick, an AlSb layer of 5ML thick and a GaSb layer of 3ML thick in sequence; through multi-period alternating growth (for example, repeating the cycle several times), the required multi-layer barrier structure can be formed to achieve the function of band regulation or suppression of carrier reverse transport.

[0067] P region structure: 8InAs / 2GaSb superlattice, about Be doping with a thickness of about 500nm is used to further modulate the energy band and facilitate coordination with the common contact layer.

[0068] Next, after the long-wave channel region is grown, a GaSb common contact layer with a thickness of about 500 nm is grown, and the Be doping concentration is about , used to form an electronic barrier between the long-wave and medium-wave channels.

[0069] Above it is the medium wave channel, which includes:

[0070] Growth of the I region structure of the (9InAs / 8GaSb) superlattice, with a Be doping concentration of about The thickness can be selected in the range of 1 to 2.5 μm. A superlattice barrier layer of (9.5InAs / 9AlSb) with a thickness of about 150 nm is formed thereon, and to Gradient Si doping (i.e., from the beginning of growth to the end of growth, the doping concentration increases from about Smoothly changes to approx. ), which is used to block majority carriers and reduce crosstalk.

[0071] Finally, the shortwave channel is grown, which includes:

[0072] The short-wave I region and P region are grown on the barrier layer, where the I region is a (5InAs / 8GaSb) superlattice with a Be doping concentration of about , thickness 1 to 2.5 μm; the P region is the same superlattice, but the Be doping concentration is increased to about , with a thickness of about 200nm, in order to achieve effective hole injection control and barrier modulation. Finally, the top electrode is formed on the top of the device.

[0073] See also Figure 2 , Figure 2 A schematic diagram of the equilibrium state energy band of a three-color infrared detector provided in an embodiment of the present application.

[0074] The black curve (Ec) at the top of the figure represents the conduction band, which is the minimum energy curve for electrons;

[0075] The middle blue curve (Ef) is the Fermi level curve;

[0076] The red curve (Ev) below represents the valence band, which is the minimum hole energy curve.

[0077] The horizontal axis device depth (μm) represents the device depth or position (with the upper electrode on the top of the device as the coordinate zero point), and the electrode thickness is 200nm. The vertical axis Energy (eV) represents energy, in electron volts (eV). Figure 2 It can be seen that at about 4.4μm, Ec has a higher potential barrier, forming an electron potential barrier between the long-wave and medium-wave channels. Photogenerated electrons cannot pass between the two channels, which can reduce the crosstalk caused by electron transport between the medium-wave and long-wave channels. This corresponds to the GaSb barrier layer between the long-wave and medium-wave channels. At the same time, the GaSb layer of about 500nm plays the role of a long-wave structure buffer layer. At 8μm, Ev is higher, which hinders the transport of holes and can reduce dark current, corresponding to the hole barrier layer in the long-wave M region.

[0078] In this device, the long-wave channel uses a PπMN structure, in which the N-type doped N region serves as the lower ohmic contact layer. The M region serves as a hole barrier layer, and a high-bandgap AlSb layer is inserted into the GaSb material in InAs / GaSb to form an M-type barrier. The high bandgap width can reduce the generation and recombination of electrons and holes and the Auger recombination process, and suppress the dark current noise caused by the reverse transport of majority-carrier holes. The absorption layer I region is lightly P-doped, and its minority carriers are electrons, which have a higher diffusion length than holes, and can improve the light response of the I region. The P region of the long-wave channel uses an 8InAs / 12GaSb superlattice, and the bandgap is higher than the long-wave absorption region, which can suppress the reverse transport of photogenerated electrons in the long-wave channel and reduce the crosstalk between the medium and long-wave channels.

[0079] It should be noted that the above PπMN structure, that is, P represents the p-type region, π represents the lightly doped p-type absorption layer, M is an M-type barrier layer composed of inserted high bandgap material AlSb, which is used to suppress the reverse transport of holes, and N is an n-type heavily doped layer providing ohmic contact for the lower electrode.

[0080] A Be-doped GaSb common contact layer is inserted between the long-wave channel and the medium-wave channel as an electron barrier, which is beneficial to suppress the reverse flow of photogenerated electrons in the absorption layers of the two bands and reduce the crosstalk between the two bands.

[0081] The medium-wave and short-wave channels adopt the PMP structure design, in which the absorption layer I region of the medium-wave and short-wave channels are lightly doped with P-type, and the minority carrier type is electron, which is conducive to improving the light response of the absorption region. Between the medium-wave I region and the short-wave I region is a 9.5InAs / 9AlSb n-type barrier layer, which is used to block the dark current caused by majority carriers.

[0082] The above-mentioned PMP structure refers to dividing the device longitudinal section into three parts: P region, M region, and P region, among which:

[0083] The P region (p-type region) is a p-type doped region, which is usually used to form a hole injection or hole collection end, as well as to regulate the energy band;

[0084] The M region (barrier region) is a barrier layer, which uses suitable materials (such as InAs / AlSb superlattice, etc.) and may be n-type or undoped to form a barrier on the conduction band or valence band to block the migration of majority carriers from adjacent regions, thereby reducing dark current and crosstalk;

[0085] The P region (the p-type region at the other end) can further provide good contact with the electrode or the upper and lower layers to achieve bias control of the device.

[0086] The three-color structure of the present invention can eliminate the etching of the middle electrode and the middle table in the common three-color device, and realize the switch control of three channels with only two electrodes. The specific control method is now described in detail.

[0087] Figure 3 The energy band diagram of the three-color infrared detector under different bias conditions, the bias is applied to the lower electrode, where the upper black curve (Ec) is the electron minimum energy curve. The lower red curve (Ev) is the hole minimum energy curve. The horizontal axis represents the position, and the top of the electrode above the horizontal axis is the coordinate zero point.

[0088] like Figure 3 As shown in (a), when a positive bias is applied, the height of the GaSb conduction band at about 4.5μm is much higher than the conduction band of the short-wave and medium-wave absorption regions, so GaSb acts as a barrier to block the photogenerated electrons in the short-wave and medium-wave channels, and the short-wave and medium-wave channels are closed. The conduction band of the 5-6μm long-wave absorption region channel is higher than the conduction band of the M-type barrier at about 7μm, so the long-wave channel is opened.

[0089] like Figure 3 As shown in (b), when a negative bias of -0.1V is applied, the electric field caused by the external bias will cause the electrons to move along the upper electrode, and the photogenerated carriers in the short-wave absorption region are collected by the upper electrode under the action of the built-in electric field, and the short-wave channel is opened. The conduction band height of the medium-wave absorption region at 3-4μm is much lower than the conduction band height of the upper electrode at about 0.2μm, so the photogenerated electrons in the medium-wave channel will be blocked and the medium-wave channel will be closed. The electrons in the 5-6μm long-wave absorption region will be blocked by the GaSb barrier at about 4.5μm, and the long-wave channel will be closed.

[0090] like Figure 3As shown in (c), as the external bias voltage is further reduced, the short-wave absorption region can still be received by the upper electrode under the action of the built-in electric field, and the conduction band height of the medium-wave absorption region at 3-4 μm gradually approaches the conduction band height of the upper electrode region at about 0.2 μm, and the conduction band height is reversed at a bias voltage of about -0.5 V, as shown in FIG. Figure 3 As shown in (d), the photogenerated electrons in the medium-wave channel can be collected by the upper electrode region, thus opening the medium-wave channel, while the long-wave channel is still closed.

[0091] In summary, the device structure design of the three-color infrared detector based on the novel gradient barrier structure described in the present invention realizes the switch of the three-color channels controlled by two electrodes. In the positive bias or zero bias state, the long-wave channel is turned on, and the medium-wave and short-wave channels are turned off; under a small negative bias, the short-wave channel is turned on, and the medium-wave and long-wave channels are turned off; when the negative bias increases to a certain extent, the short-wave and medium-wave channels are turned on, and the long-wave channel is turned off.

[0092] It should be understood that in various embodiments of the present invention, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0093] It should be understood that determining B based on A does not mean determining B only based on A. B can also be determined based on A and / or other information.

[0094] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed in the present invention can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0095] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. 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 invention. 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 can be combined in any one or more embodiments or examples in a suitable manner.

[0096] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A three-color infrared detector based on a new gradient barrier structure, characterized in that: include: A short-wave channel region, the short-wave channel region comprising: a short-wave I region superlattice structure, including an InAs / GaSb stack, and lightly p-type doped; a short-wave P region superlattice structure, the doping concentration of which is greater than the doping concentration of the short-wave I region, and is used to provide an upper electrode ohmic contact; The graded barrier layer is located between the short-wave channel and the medium-wave channel. The graded barrier layer includes an InAs / AlSb stack and is to Gradient n-type doping; The medium wave channel region includes: a medium wave I region superlattice structure, which adopts an InAs / GaSb stack and is lightly p-type doped; a medium wave P region; a common contact layer, which includes a GaSb material and is heavily p-type doped, and is used to form an electron barrier between the medium wave channel and the long wave channel; The long-wave channel region includes: a long-wave I region superlattice structure, which adopts InAs / GaSb stacking and is lightly p-type doped; an M-type barrier layer in the M region, in which an AlSb layer is inserted into the long-wave I region or adjacent to it to form an M-type barrier for inhibiting the reverse transport of holes; an N-type doped layer in the N region, which is located below the long-wave I region or the M region and is used to provide an ohmic contact with the lower electrode; A lower electrode substrate structure, the lower electrode substrate structure comprising: a GaSb substrate; a buffer layer located on the GaSb substrate; The three-color infrared detector is only provided with an upper electrode and a lower electrode, and bias voltages of different polarities and amplitudes are applied to the lower electrode to respectively open or close the three detection channels of short wave, medium wave and long wave.

2. The three-color infrared detector based on the novel gradient barrier structure according to claim 1 is characterized in that: The short-wave I region adopts 5InAs / 8GaSb superlattice stacking, and the p-type light doping concentration is , thickness is 1 to 2.5 μm; The short-wave P region is made of the same material stack as the short-wave I region and is heavily p-doped with a concentration of , thickness is 200nm.

3. The three-color infrared detector based on the novel gradient barrier structure according to claim 2 is characterized in that: The medium-wave region I adopts 9InAs / 8GaSb superlattice stacking, and the p-type light doping concentration is , thickness is 1 to 2.5 μm.

4. The three-color infrared detector based on the novel gradient barrier structure according to claim 3 is characterized in that: The long-wave I region adopts 12.5InAs / 7GaSb superlattice stacking, and the p-type light doping concentration is , thickness is 1 to 2.5 μm; The M region adopts a 18InAs / 3GaSb / 5AlSb / 3GaSb stacked structure with a thickness of 500nm; The N region adopts a 18InAs / 3GaSb / 5AlSb / 3GaSb stacked structure and is n-type doped with a concentration of .

5. The three-color infrared detector based on the novel gradient barrier structure according to claim 4 is characterized in that: The common contact layer is composed of GaSb, and the p-type doping concentration is , thickness is 500nm.

6. The three-color infrared detector based on the novel gradient barrier structure according to claim 5, characterized in that: The InAs / AlSb superlattice period number of the graded barrier layer is 9.5 / 9 periods, and the total thickness is 150nm.

7. The three-color infrared detector based on the novel gradient barrier structure according to claim 6, characterized in that: The working modes of the three-color infrared detector when biased include: In response to the positive bias applied to the lower electrode, the long-wave channel is turned on and the short-wave and medium-wave channels are closed; In response to a negative bias voltage applied to the lower electrode and the bias voltage being in the range of -0.1V to -0.5V, the short wave channel is turned on, and the medium wave and long wave channels are turned off; In response to a negative bias voltage being applied to the lower electrode and the bias voltage being less than or equal to -0.5 V, the short wave and medium wave channels are turned on, and the long wave channel is turned off.

8. The three-color infrared detector based on the novel gradient barrier structure according to claim 7, characterized in that: The buffer layer has a Te doping concentration of GaSb buffer layer with a thickness of 988nm.

9. The three-color infrared detector based on the novel gradient barrier structure according to claim 8, characterized in that: The growth method of the three-color infrared detector is molecular beam epitaxy or metal organic chemical vapor deposition.

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