Two-dimensional material composite type-Ⅱ superlattice infrared detector and preparation method thereof

Abstract

This invention relates to a two-dimensional material composite type II superlattice infrared detector and its fabrication method, belonging to the field of infrared detector fabrication technology. This invention mainly utilizes the tunable band structure and unique physical properties of two-dimensional materials (such as tungsten diselenide (WSe2) and molybdenum disulfide (MoS2)). Through band alignment, a stepped photoelectron path is formed in the conduction band, and a hole barrier structure is formed in the valence band, which can effectively block noise without affecting the photocurrent. The specific structure of the two-dimensional material composite type II superlattice infrared detector disclosed in this invention, from bottom to top, includes an N-type doped GaSb substrate layer, a P-type doped GaSb transition layer, a weakly P-type undoped InAs / GaSb type II superlattice absorption layer, a weakly P-type undoped tungsten diselenide (WSe2) layer, a weakly N-type undoped molybdenum disulfide (MoS2) layer, and a metal electrode. It features majority carrier blocking, high sensitivity, and fast response, thus improving the device's detection performance.

Description

Technical Field

[0001] This invention belongs to the field of infrared detector fabrication technology, and relates to a two-dimensional material composite type II superlattice infrared detector and its fabrication method. Background Technology

[0002] Traditional infrared detector materials such as quantum wells, mercury cadmium telluride, and type-II superlattices are developing towards higher performance and lower cost. Among them, type-II superlattices have advantages such as a wide tunable bandgap range, high effective electron mass, suppression of Auger recombination, and high uniformity, exhibiting excellent device performance from the mid-wavelength to the very long-wavelength range. Type-II superlattices (T2SLs), represented by InAs / GaSb and InAs / InAsS, are gradually becoming the preferred materials for third-generation infrared focal plane detectors.

[0003] In recent years, barrier-type T2SL infrared detectors have developed rapidly. Aluminum (Al)-based barrier designs have effectively improved the performance of T2SL infrared detectors, evolving from the initial unipolar barriers to the current bipolar barriers, achieving high-efficiency detection. However, they are still constrained by factors such as poor stability, difficulty in heteroepitaxial growth of barrier structures, and large dark current. Barrier structures based on two-dimensional materials, on the other hand, have no dangling bonds on their surface, can transcend lattice matching constraints, and are easily integrated with other bulk materials. They also possess advantages such as tunable band structure, room temperature operation, high gain, and fast response speed.

[0004] Therefore, combining two-dimensional materials with type II superlattice technology through band barrier design research can help reduce device noise, enhance response, and improve device detection performance. Summary of the Invention

[0005] In view of this, one objective of the present invention is to provide a two-dimensional material composite type II superlattice infrared detector; another objective of the present invention is to provide a method for preparing a two-dimensional material composite type II superlattice infrared detector.

[0006] To achieve the above objectives, the present invention provides the following technical solution: 1. A two-dimensional material composite type II superlattice infrared detector, wherein the infrared detector contains a two-dimensional material barrier layer, wherein the two-dimensional material barrier layer is constructed by stacking tungsten diselenide (WSe2) layer and molybdenum disulfide (MoS2) layer; The infrared detector has a weakly P-type undoped tungsten diselenide (WSe2) layer and a weakly N-type undoped molybdenum disulfide (MoS2) layer sequentially disposed between the type II superlattice absorption layer and the metal electrode.

[0007] Preferably, the carrier concentration of the weakly p-type undoped tungsten diselenide (WSe2) layer is on the order of 10. 11 ~10 13cm 3 Thickness is 2~10nm; The carrier concentration of the weakly N-type undoped molybdenum disulfide (MoS2) layer is on the order of 10. 10 ~10 12 cm 3 The thickness is 2~10nm.

[0008] Preferably, the infrared detector further includes a transition layer and a substrate layer located sequentially below the type II superlattice absorption layer.

[0009] Preferably, the type II superlattice absorption layer is a weakly p-type undoped InAs / GaSb type II superlattice absorption layer with a thickness of 1000 nm to 2000 nm and a carrier concentration on the order of 10. 16 cm 3 ; The substrate is an N-type doped GaSb substrate with a doping concentration on the order of 10. 17 cm 3 ; The transition layer is a p-type doped GaSb transition layer with a doping concentration on the order of 10. 18 cm 3 .

[0010] Preferably, the metal electrode is a Ti / Au alloy.

[0011] 2. The fabrication method of the above-mentioned two-dimensional material composite type II superlattice infrared detector is carried out sequentially by molecular beam epitaxy, photolithography, wet etching, wet transfer, and plasma etching. The fabrication method includes the following steps: (1) A P-type Be-doped GaSb transition layer is grown on an N-type Te-doped GaSb substrate; (2) An absorption layer is formed by growing InAs / GaSb type II superlattice material on the P-type doped GaSb transition layer; (3) The mask pattern is transferred to the epitaxial thin film by photolithography and then etched onto the P-type Be-doped GaSb transition layer by wet etching to prepare the formation unit superlattice detector mesa; (4) The CVD-grown tungsten diselenide (WSe2) film is transferred to the InAs / GaSb type II superlattice absorption layer by wet transfer to form a tungsten diselenide (WSe2) layer; (5) The molybdenum disulfide (MoS2) film grown by CVD method is transferred to the surface of tungsten diselenide (WSe2) layer by wet transfer to form a molybdenum disulfide (MoS2) layer; (6) The tungsten diselenide (WSe2) film and molybdenum disulfide (MoS2) film outside the unit superlattice detector mesa are removed sequentially by double-layer photoresist exposure and plasma etching methods; (7) Metal electrodes were fabricated on the molybdenum disulfide (MoS2) layer and the P-type Be-doped GaSb transition layer by photolithography masking and vapor deposition.

[0012] Preferably, in step (4), the wet transfer specifically involves: growing tungsten diselenide (WSe2) on a sapphire substrate, cleaning it sequentially with liquid nitrogen, LiI aqueous solution, and deionized water, then spin-coating polymethyl methacrylate (PMMA) onto the surface of tungsten diselenide (WSe2), heating and drying it, then cutting it to leave a gap in the tungsten diselenide (WSe2) layer, and obliquely inserting it into deionized water to detach the sapphire growth substrate, thereby obtaining a tungsten diselenide (WSe2) film with polymethyl methacrylate (PMMA) attached, using the unit superlattice detector platform as a substrate to receive it, heating and drying it, and then soaking it in acetone to remove polymethyl methacrylate (PMMA), thereby transferring tungsten diselenide (WSe2) to the surface of the InAs / GaSb II type superlattice absorption layer to form a tungsten diselenide (WSe2) layer.

[0013] Preferably, in step (5), the wet transfer specifically involves: growing molybdenum disulfide (MoS2) on a glass substrate, cleaning it sequentially in liquid nitrogen, LiI aqueous solution, and deionized water, then spin-coating polymethyl methacrylate (PMMA) onto the molybdenum disulfide (MoS2), heating and drying it, then cutting it to leave a gap in the molybdenum disulfide (MoS2) layer, and obliquely inserting it into deionized water to detach the glass substrate, thereby obtaining a molybdenum disulfide (MoS2) film with polymethyl methacrylate (PMMA) attached, using the tungsten diselenide (WSe2) layer as a substrate, heating and drying it, and then soaking it in acetone to remove the polymethyl methacrylate (PMMA), thereby transferring molybdenum disulfide (MoS2) to the surface of the tungsten diselenide (WSe2) layer to form a molybdenum disulfide (MoS2) layer.

[0014] The beneficial effects of this invention are as follows: This invention discloses a two-dimensional material composite type II superlattice infrared detector and its preparation method. It mainly utilizes the tunable band structure and unique physical properties of two-dimensional materials (such as tungsten diselenide (WSe2) and molybdenum disulfide (MoS2)). Through band alignment, the conduction band forms a stepped photoelectron path, and the valence band forms a hole barrier structure, which can effectively block noise without affecting the photocurrent. The specific structure of the two-dimensional material composite type II superlattice infrared detector disclosed in this invention includes, from bottom to top, an N-type doped GaSb substrate layer, a P-type doped GaSb transition layer, a weakly P-type undoped InAs / GaSb type II superlattice absorption layer, a weakly P-type undoped tungsten diselenide (WSe2) layer, a weakly N-type undoped molybdenum disulfide (MoS2) layer, and a metal electrode. Among them, WSe2 and MoS2 are stacked on each other. By combining with the type II superlattice, a barrier layer is constructed, which can effectively reduce surface leakage current and majority carrier dark current, thereby improving device performance. It has the characteristics of majority carrier blocking, high sensitivity, and fast response, and can improve the detection performance of infrared detectors.

[0015] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 The two-dimensional material composite type II superlattice infrared detector in Example 1 is shown under an optical microscope; Figure 2 This is a schematic diagram of the structure of the two-dimensional material composite type II superlattice infrared detector in Example 1; Figure 3 The band structure of the two-dimensional material composite type II superlattice infrared detector prepared in Example 1 is shown. Figure 4 The dark current density-voltage relationship curves are shown for the non-composite two-dimensional material superlattice device (Ref) in the comparative examples and the two-dimensional material composite type II superlattice infrared detector (with 2D) prepared in Example 1. Figure 5 The photoresponse curves of the non-composite two-dimensional material superlattice device (Ref) in the comparative example and the two-dimensional material composite type II superlattice infrared detector (with 2D) prepared in Example 1 under 9μm switching conditions are shown. Detailed Implementation

[0017] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0018] Example 1 A two-dimensional composite type II superlattice infrared detector comprises, from bottom to top, an N-type doped GaSb substrate, a P-type doped GaSb transition layer, a weakly P-type undoped InAs / GaSb type II superlattice absorption layer, a weakly P-type undoped tungsten diselenide (WSe2) layer, a weakly N-type undoped molybdenum disulfide (MoS2) layer, and a metal electrode. The two-dimensional composite type II superlattice infrared detector under an optical microscope is shown below. Figure 1 The schematic diagram of the structure of the two-dimensional material composite type II superlattice infrared detector is shown below. Figure 2 As shown, the material is fabricated sequentially through molecular beam epitaxy, photolithography, wet etching and wet transfer, and plasma etching. The specific fabrication method is as follows: (1) On an N-type Te-doped GaSb substrate (with a doping concentration of 1×10⁻⁶), 17 A p-type Be-doped GaSb transition layer (with a doping concentration of 2 × 10⁻⁶) is grown on the substrate. 18 ); (2) An absorption layer (with a thickness of 2 μm and a carrier concentration of 1 × 10⁻⁶) is formed by growing InAs / GaSb type II superlattice material on the P-type doped GaSb transition layer. 16 ;); (3) The mask pattern is transferred to the epitaxial thin film by photolithography and then etched onto the P-type Be-doped GaSb transition layer by wet etching to prepare the formation unit superlattice detector mesa; (4) The CVD-grown tungsten diselenide (WSe2) film (10 nm thick) was transferred to the surface of the InAs / GaSb II superlattice absorption layer by wet transfer (the specific method is as follows: tungsten diselenide (WSe2) was grown on a sapphire substrate and washed in liquid nitrogen, LiI aqueous solution and deionized water in sequence. Then, polymethyl methacrylate (PMMA) was spin-coated on the surface of tungsten diselenide (WSe2). After heating and drying, it was cut to leave a gap in the tungsten diselenide (WSe2) layer. It was then obliquely inserted into deionized water to remove the sapphire growth substrate and obtain a tungsten diselenide (WSe2) film with polymethyl methacrylate (PMMA). The unit superlattice detector platform was used as the substrate to receive the film. After heating and drying, it was soaked in acetone to remove polymethyl methacrylate (PMMA). Thus, tungsten diselenide (WSe2) was successfully transferred to the surface of the InAs / GaSb II superlattice absorption layer to form a tungsten diselenide (WSe2) layer. (5) The CVD-grown molybdenum disulfide (MoS2) film (10 nm thick) was transferred to the surface of the tungsten diselenide (WSe2) layer by wet transfer (the specific method is as follows: molybdenum disulfide (MoS2) was grown on a glass substrate, and washed in liquid nitrogen, LiI aqueous solution and deionized water in sequence. Then, polymethyl methacrylate (PMMA) was spin-coated on the surface of molybdenum disulfide (MoS2). After heating and drying, it was cut to leave a gap in the molybdenum disulfide (MoS2) layer. The glass substrate was then detached by obliquely inserting it into the deionized water to obtain a molybdenum disulfide (MoS2) film with polymethyl methacrylate (PMMA) attached. The tungsten diselenide (WSe2) layer was used as a substrate to support the film. After heating and drying, the film was soaked in acetone to remove polymethyl methacrylate (PMMA), thereby successfully transferring molybdenum disulfide (MoS2) to the surface of the tungsten diselenide (WSe2) layer), forming a molybdenum disulfide (MoS2) layer. (6) Remove two-dimensional materials outside the mesa by double-layer photoresist exposure and plasma etching process. (7) Ti / Au alloys were prepared as metal electrodes on the molybdenum disulfide (MoS2) layer and the P-type Be-doped GaSb transition layer, respectively, by photolithography masking and vapor deposition.

[0019] Comparative Examples Prepared according to the method of Example 1, except that the preparation of the tungsten diselenide (WSe2) layer in step (4), the molybdenum disulfide (MoS2) layer in step (5), and step (6) is omitted. Ti / Au alloy is directly prepared on the P-type Be-doped GaSb transition layer as two metal electrodes, resulting in an uncomposite two-dimensional material superlattice device consisting of an N-type doped GaSb substrate layer, a P-type Be-doped GaSb transition layer, a weakly P-type undoped InAs / GaSb type II superlattice absorption layer, and metal electrodes from bottom to top.

[0020] Figure 3 This is the band structure diagram of the two-dimensional material composite type II superlattice infrared detector prepared in Example 1. From... Figure 3 It can be seen that the three materials (molybdenum disulfide (MoS2), tungsten diselenide (WSe2), and InAs / GaSb) form a special hole-blocking band structure, allowing photocarriers in the conduction band to pass through smoothly; the stacking of MoS2 and WSe2 in the valence band creates a large hole barrier, which can effectively reduce surface leakage current and majority carrier dark current. Figure 4 To compare the dark current density-voltage relationship curves of the non-composite two-dimensional material superlattice device (Ref) in the examples and the two-dimensional material composite type II superlattice infrared detector (with 2D) prepared in Example 1, from... Figure 4 It can be seen that the two-dimensional material composite type II superlattice infrared detector prepared in Example 1 has a dark current density of 2 × 10⁻⁶ under zero bias. -7 A·cm -2 Compared to the non-composite two-dimensional material superlattice device in the comparative examples (Ref) (10) -3 A·cm -2 The dark current was suppressed by about 4 orders of magnitude, demonstrating that the two-dimensional material composite type II superlattice infrared detector with a two-dimensional material barrier layer prepared in Example 1 has good dark current blocking.

[0021] Figure 5 This section presents the photoresponse-time curves under 9μm switching conditions for a comparative example of the non-composite two-dimensional material superlattice device (Ref) and the two-dimensional material composite type II superlattice infrared detector (with 2D) prepared in Example 1. Figure 5 As can be seen, in Example 1, the dark current of the two-dimensional material composite type II superlattice infrared detector was significantly reduced after being modified with two two-dimensional materials, molybdenum disulfide and tungsten diselenide, while the photocurrent was not significantly suppressed and the photoresponse was enhanced.

[0022] Furthermore, in the above embodiments, the order of magnitude of the carrier concentration in the weakly p-type undoped tungsten diselenide layer can vary from 10. 11 ~10 13 cm 3 The thickness can vary from 2 to 10 nm, and the carrier concentration of the weakly N-type undoped molybdenum disulfide layer can vary from the order of magnitude to 10. 10 ~10 12 cm 3 The thickness can vary from 2 to 10 nm, and the thickness of the weakly p-type undoped InAs / GaSb type II superlattice absorber layer can vary from 1000 nm to 2000 nm. The order of magnitude of the carrier concentration can vary from 10. 16 cm 3The doping concentration of the N-type doped GaSb substrate can vary on the order of 10. 17 cm 3 The doping concentration of the p-type doped GaSb transition layer can vary on the order of 10. 18 cm 3 The performance of the two-dimensional material composite type II superlattice infrared detector formed after the modification is similar to that of the two-dimensional material composite type II superlattice infrared detector in Example 1. It has the characteristics of majority carrier blocking, high sensitivity and fast response, which can improve the detection performance of the device.

[0023] In summary, this invention discloses a two-dimensional material composite type II superlattice infrared detector and its fabrication method. It mainly utilizes the tunable band structure and unique physical properties of two-dimensional materials (such as tungsten diselenide (WSe2) and molybdenum disulfide (MoS2)). Through band alignment, a stepped photoelectron path is formed in the conduction band, and a hole barrier structure is formed in the valence band, effectively blocking noise without affecting the photocurrent. The specific structure of the two-dimensional material composite type II superlattice infrared detector disclosed in this invention, from bottom to top, includes an N-type doped GaSb substrate layer, a P-type doped GaSb transition layer, a weakly P-type undoped InAs / GaSb type II superlattice absorption layer, a weakly P-type undoped tungsten diselenide (WSe2) layer, a weakly N-type undoped molybdenum disulfide (MoS2) layer, and a metal electrode. It features majority carrier blocking, high sensitivity, and fast response, thus improving the device's detection performance.

[0024] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A two-dimensional material composite type II superlattice infrared detector, characterized in that, The infrared detector consists of, from bottom to top, an N-type doped GaSb substrate, a P-type doped GaSb transition layer, a weakly P-type undoped InAs / GaSb type II superlattice absorption layer, a weakly P-type undoped tungsten diselenide layer, and a weakly N-type undoped molybdenum disulfide layer. InAs / GaSb II superlattice material is grown on the P-type doped GaSb transition layer to form a weakly P-type undoped InAs / GaSb II superlattice absorption layer. The mask pattern is transferred to the epitaxial thin film by photolithography and then etched onto the P-type doped GaSb transition layer by wet etching to form a mesa. Metal electrodes are respectively disposed on the mesa of the weakly N-type undoped molybdenum disulfide layer and the P-type doped GaSb transition layer.

2. The two-dimensional material composite type II superlattice infrared detector according to claim 1, characterized in that, The carrier concentration of the weakly P-type undoped tungsten diselenide layer is on the order of 10. 11 ~10 13 cm 3 Thickness is 2~10nm; The carrier concentration of the weakly N-type undoped molybdenum disulfide layer is on the order of 10. 10 ~10 12 cm 3 The thickness is 2~10nm.

3. The two-dimensional material composite type II superlattice infrared detector according to claim 1, characterized in that, The thickness of the weakly P-type undoped InAs / GaSb type II superlattice absorber layer is 1000 nm to 2000 nm, and the carrier concentration is on the order of 10. 16 cm 3 ; The doping concentration of the N-type doped GaSb substrate is on the order of 10. 17 cm 3 ; The doping concentration of the p-type doped GaSb transition layer is on the order of 10. 18 cm 3 .

4. The two-dimensional material composite type II superlattice infrared detector according to claim 1, characterized in that, The metal electrode is a Ti / Au alloy.

5. A method for fabricating a two-dimensional material composite type II superlattice infrared detector according to any one of claims 1 to 4, comprising fabricating the detector sequentially by molecular beam epitaxy, photolithography, wet etching, wet transfer, and plasma etching, characterized in that, The preparation method includes the following steps: (1) A P-type Be-doped GaSb transition layer is grown on an N-type Te-doped GaSb substrate; (2) An absorption layer is formed by growing InAs / GaSb type II superlattice material on the P-type doped GaSb transition layer; (3) The mask pattern is transferred to the epitaxial thin film by photolithography and then etched onto the P-type Be-doped GaSb transition layer by wet etching to prepare the formation unit superlattice detector mesa; (4) The tungsten diselenide thin film grown by CVD method is transferred to the InAs / GaSb type II superlattice absorption layer by wet transfer to form a tungsten diselenide layer; (5) The molybdenum disulfide film grown by CVD method is transferred to the surface of tungsten diselenide layer by wet transfer to form a molybdenum disulfide (MoS2) layer; (6) The tungsten diselenide film and molybdenum disulfide film outside the mesa of the unit superlattice detector are removed sequentially by double-layer photoresist exposure and plasma etching methods; (7) Metal electrodes were fabricated on the molybdenum disulfide layer and the P-type Be-doped GaSb transition layer by photolithography masking and vapor deposition.

6. The preparation method according to claim 5, characterized in that, In step (4), the wet transfer specifically involves: growing tungsten diselenide on a sapphire substrate, cleaning it sequentially in liquid nitrogen, LiI aqueous solution, and deionized water, then spin-coating polymethyl methacrylate onto the tungsten diselenide surface, heating and drying it, cutting it to leave a gap in the tungsten diselenide layer, and obliquely inserting it into deionized water to detach the sapphire growth substrate, thereby obtaining a tungsten diselenide film coated with polymethyl methacrylate. The unit superlattice detector platform is used as the substrate to receive it, and after heating and drying, it is soaked in acetone to remove the polymethyl methacrylate, thereby transferring tungsten diselenide to the surface of the InAs / GaSb II type superlattice absorption layer to form a tungsten diselenide layer.

7. The preparation method according to claim 5, characterized in that, In step (5), the wet transfer specifically involves: growing molybdenum disulfide on a glass substrate, cleaning it sequentially in liquid nitrogen, LiI aqueous solution and deionized water, then spin-coating polymethyl methacrylate onto the molybdenum disulfide, heating and drying it, cutting it to leave a gap in the molybdenum disulfide layer, and obliquely inserting it into deionized water to detach the glass substrate, thereby obtaining a molybdenum disulfide film with polymethyl methacrylate attached, using the tungsten diselenide layer as a substrate to receive it, heating and drying it, and then soaking it in acetone to remove the polymethyl methacrylate, thereby transferring molybdenum disulfide to the surface of the tungsten diselenide layer to form a molybdenum disulfide layer.

Images