MXene-Si-MXene van der Waals photoelectric detector with synergistic light trapping effect

Abstract

The invention discloses an MXene-Si-MXene van der Waals photoelectric detector with a synergistic light trapping effect, which is characterized in that monocrystalline silicon is used as a substrate, and a pair of patterned MXene films arranged at intervals are formed on the surface of the substrate; the structure of each patterned MXene thin film comprises an electrode part and a functional part integrally extending from one side of the electrode part to the other patterned MXene thin film; a channel is formed in a gap between the functional parts of the two patterned MXene thin films, and the two functional parts and silicon in the channel form an MXene-Si-MXene van der Waals structure; and an MXene thin layer is arranged in the channel so as to form a synergistic light trapping effect. The prepared detector has the advantages of being large in responsivity, high in response speed, good in stability, high in detection rate and the like, and meanwhile has the advantages of being easy to prepare, low in cost and the like.

Description

Technical Field

[0001] The present invention relates to a MXene-Si-MXene van der Waals photodetector with a synergistic light trapping effect, belonging to the technical field of semiconductor photoelectric devices. Background Art

[0002] Photodetectors are widely used in daily life, such as environmental monitoring, medical imaging, optical communications, security inspection, life sciences, etc. However, the increasingly complex application environment also puts forward higher requirements for traditional photodetectors, such as high gain-bandwidth product (GBP), simple device structure, and low cost.

[0003] In traditional devices, high gain and high bandwidth are usually in conflict and cannot be met at the same time. Avalanche photodiodes (APDs) achieve high GBP, but they are complex in structure and relatively expensive, so they still face huge obstacles and complex manufacturing processes. Common metal-semiconductor-metal (MSM) photodiodes are attractive in meeting bandwidth requirements due to their ease of manufacture, but they still face some limitations in high sensitivity. In order to improve the sensitivity, people have tried to introduce various physical mechanisms such as the light gating effect, which significantly increases the gain, but cannot meet the high bandwidth requirements. Therefore, it is of great significance to develop a photodetector that is cheap, simple in structure, and meets both high gain and high bandwidth.

[0004] MXenes are a class of two-dimensional materials with broad development prospects. Due to their excellent metallic conductivity, biocompatibility, large specific surface area and rich surface chemical properties, they have great potential in optical and electrical devices. [1] It is disclosed that MXene has excellent optical and electrical properties such as adjustable work function, high transmittance, high conductivity, no dangling bonds on the surface, and electrode preparation can be achieved through van der Waals (vdW) contact. It is expected to solve important problems such as the barrier height of traditional photodetectors that are difficult to improve. However, it still has problems such as low responsiveness, low detection rate and small bandwidth, which limit its application.

[0005] Therefore, the MXene-Si-MXene van der Waals photodetector that combines the MSM structure with the synergistic light-trapping effect produced by the optical gating mechanism is not only simple in structure and low in cost, but also meets the requirements of high gain-bandwidth product, and has great application potential in the future.

[0006] References:

[0007] 1.Luo,L.,Huang,Y.,Cheng,K.et al.MXene-GaN van der Waals metal-semiconductorjunctions for high performance multiple quantum wellphotodetectors.Light Sci Appl 10,177(2021).https: / / doi.org / 10.1038 / s41377-021-00619-1. Summary of the invention

[0008] In view of the shortcomings and deficiencies of the above-mentioned prior art, the present invention provides a MXene-Si-MXene van der Waals photodetector with a synergistic light trapping effect, aiming to obtain a low-cost, high gain-bandwidth product photodetector.

[0009] In order to solve the technical problem, the present invention adopts the following technical solution:

[0010] A MXene-Si-MXene van der Waals photodetector with a synergistic light trapping effect, characterized in that: the photodetector uses single crystal silicon as a substrate, and a pair of patterned MXene films arranged at intervals are formed on the surface of the substrate; the structure of each patterned MXene film includes an electrode portion, and a functional portion extending from one side of the electrode portion toward another patterned MXene film in an integrated manner; the interval between the functional portions of the two patterned MXene films forms a channel, and the two functional portions and the silicon in the channel constitute a MXene-Si-MXene van der Waals structure; a MXene thin layer is arranged in the channel to form a synergistic light trapping effect.

[0011] Furthermore, the thickness of the substrate is 100 μm-500 μm.

[0012] Furthermore, the thickness of the patterned MXene film is 1 μm-5 μm.

[0013] Further: the electrode part is square with a side length of 1500-2000 μm. The functional part is rectangular with a length of 700-1000 μm and a width of 150-200 μm, and a short side forming the "width" of the functional part is located on one side of the electrode part. The channel between the two functional parts is 700-1000 μm long and 50-100 μm wide, and the length direction of the channel is the long side direction of the functional part (therefore, it is equal to the length of the functional part), and the width direction of the channel is the short side direction of the functional part.

[0014] The thickness of the MXene thin layer is 0.1 to 0.3 μm.

[0015] Furthermore, the method for preparing the patterned MXene film is as follows: a mask matching the structure of the patterned MXene film is set, the mask is fixed above the substrate, a solution of MXene material is dripped on the substrate using the mask, and a patterned MXene film is formed after drying; at the same time, the dripped solution diffuses into the channel between the functional parts of the two patterned MXene films to form a MXene thin layer.

[0016] Furthermore: by controlling the thickness of the mask, the thickness of the patterned MXene film is controlled; by controlling the clamping degree of the mask and the substrate, the diffusion of the solution in the channel is controlled, thereby controlling the thickness of the MXene thin layer.

[0017] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0018] The photoelectric detector prepared by the present invention has high sensitivity, high Schottky barrier height, fast response speed and high detection rate. At the same time, the preparation method of the photoelectric detector of the present invention has the advantages of simplicity, strong compatibility, high stability and easy preparation of large-area devices. It has broad application prospects in the research and development of low-cost, high-speed, stable and highly integrated detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the structure of the photodetector of the present invention, where numbers 1 is single crystal silicon, 2 is the electrode part, 3 is the functional part, and 4 is the MXene thin layer.

[0020] Figure 2 Schematic diagram of the design of the mask used to prepare the patterned MXene film in Example 1, where the left picture corresponds to the pattern plate and the right picture corresponds to the substrate plate.

[0021] Figure 3 The relevant responsivity (R) and external quantum efficiency (EQE) curves of the photodetector of Example 1 under light irradiation of different wavelengths.

[0022] Figure 4 It is a normalized enlarged schematic diagram of a single light response cycle of the photodetector of Example 1 at 0.2 KHz and the Schottky photodetector at 22 KHz.

[0023] Figure 5 This is a normalized photovoltage curve of a single response cycle of the photodetector of Example 1 at a pulse light frequency of 200 kHz.

[0024] Figure 6The bandwidth and responsivity of the photodetector of Example 1 are compared with those of commercial avalanche detectors and other Schottky photodiodes reported previously.

[0025] Figure 7 The response curve of the photodetector of Example 1 to different light intensities under a bias voltage of -1V and 850nm light illumination varies with time.

[0026] Figure 8 The dependence curve of the light intensity and photocurrent of the photodetector of Example 1 under the bias voltage of -1V and 2V and 850nm light.

[0027] Fig. 9 The photodetection rate and gain-bandwidth product of the photodetector of Example 1 under a bias voltage of 2 V and under 850 nm light of different light intensities.

[0028] Fig.10 The light response curves of the photodetectors of Examples 1, 2, 3, and 4 under -1V bias voltage and 850nm light change over time. DETAILED DESCRIPTION

[0029] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0030] Example 1

[0031] like Figure 1 As shown, the MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect provided in this embodiment uses a single crystal silicon 1 as a substrate, and a pair of patterned MXene films arranged at intervals are formed on the surface of the substrate; the structure of each patterned MXene film includes an electrode portion 2, and a functional portion 3 extending integrally from one side of the electrode portion toward the other patterned MXene film; the interval between the functional portions of the two patterned MXene films forms a channel, and the two functional portions and the silicon in the channel constitute a MXene-Si-MXene van der Waals structure; a MXene thin layer 4 is arranged in the channel to form a synergistic light trapping effect.

[0032] Specifically, in this embodiment: the thickness of the single crystal silicon used is 500 μm. The patterned MXene film formed is Ti3C2T xMXene film, 3μm thick. The electrode part is square with a side length of 2000μm. The functional part is rectangular, 1000μm long and 200μm wide, and the short side that forms the "width" of the functional part is located on one side of the electrode part. The channel between the two functional parts is 1000μm long and 100μm wide. The length direction of the channel is the long side direction of the functional part (therefore, it is equal to the length of the functional part), and the width direction of the channel is the short side direction of the functional part. The thickness of the MXene thin layer in the silicon channel is 0.2μm

[0033] The method for preparing the photoelectric detector of this embodiment comprises the following steps:

[0034] a. Wash a 10*10 mm single crystal Si in acetone, ethanol, and deionized water for 5 minutes in turn to remove organic matter on the surface.

[0035] b. Take Figure 2 The mask shown in the figure includes a pattern plate and a substrate plate. The single crystal silicon is placed between the two parts, and then the pattern plate and the substrate plate are fixed through the threaded holes around them, and the single crystal silicon is clamped. Ti3C2T is dripped onto the substrate through the pattern through hole on the pattern plate. x The solution of MXene material is then transferred to a 60°C drying table for drying to form a patterned MXene film; at the same time, the added solution diffuses into the channel between the functional parts of the two patterned MXene films to form a MXene thin layer, that is, a MXene-Si-MXene van der Waals photodetector with a synergistic light trapping effect is obtained, which is denoted as SPE-PD.

[0036] c. Apply silver paste to the electrode parts of the two patterned MXene films for testing.

[0037] For comparison, this embodiment also prepares a traditional Schottky structure photodetector: MXene material is coated on the exposed silicon and dried as a Schottky contact electrode, and In / Ga slurry silicon wafer is coated on the substrate as an ohmic contact electrode. The MXene film forms a Schottky junction with the silicon substrate.

[0038] Figure 3 The responsivity (R) and external quantum efficiency (EQE) curves of the photodetector of Example 1 under different wavelengths of irradiation calculated under the condition of a bias voltage of -1 V. The peak responsivity reaches 125.6 A / W at 850 nm, corresponding to an EQE of 2×10 4 %.

[0039] Figure 4It is a normalized magnified schematic diagram of a single light response period of the photodetector of Example 1 at 0.2 KHz and the Schottky photodetector at 22 KHz. It can be seen that the normalized time-resolved light response of Example 1 is significantly better than that of the traditional Schottky diode.

[0040] Figure 5 The normalized photovoltage curve of a single response cycle of the photodetector of Example 1 at a pulse light frequency of 200 kHz is shown. The rise / fall time is calculated to be 0.6 / 1.8 μs, respectively, which has a relatively high response speed.

[0041] Figure 6 The bandwidth and responsivity of the photodetector of Example 1 are compared with those of commercial avalanche detectors and other Schottky photodiodes reported previously. It can be clearly seen that with TMDCs / Si (Y.Zhang, Y.Yu, L.Mi, H.Wang, Z.Zhu, Q.Wu, Y.Zhang, and Y.Jiang, "In situ fabrication of vertical multilayered MoS2 / Si homotype heterojunction for high-speed visible–near-infrared photodetectors, "small, vol. 12, no. 8, pp. 1062-1071, Jan. 2016, doi: 10.1002 / smll.201502923) and graphene (Gr) / Si (C. Wang, Y. Dong, Z. Lu, S. Chen, K. Xu, Y. Ma, G. Xu, X. Zhao, and Y. Yu, "High responsivity and high-speed 1.55μminfraredphotodetector from self-powered graphene / Si heterojunction,"Sens.Actuator APhys., vol. 291, pp. 87-92, 2019 / 06 / 01 / 2019, doi: 10.1016 / j.sna.2019.03.054.) and MXene / Si Schottky diodes, the photodetector of the present invention exhibits a bandwidth of up to 200kHz, which is much higher than other diodes. Compared with Thorlabs APDs (specific model APD440A), the bandwidth of the photodetector of the present invention exceeds some models, and the responsivity at low bias voltage far exceeds most current models.

[0042] Figure 7The response curve of the photodetector of Example 1 to different light intensities under -1V bias voltage and 850nm light illumination varies with time. From the measurement results, it can be seen that the device has a stable current switching ratio.

[0043] Figure 8 The dependence curve of the light intensity and the photocurrent of the photodetector of Example 1 under the bias voltage of -1V and 2V and 850nm light is shown in FIG. It can be clearly seen from the figure that the incident light intensity and the corresponding photocurrent value present a good linear relationship.

[0044] Fig. 9 The detection rate and gain bandwidth product of the photodetector of Example 1 under the bias voltage of 2V and under 850nm light of different light intensities. Under the bias voltage of 2V, the detection rate of the photodetector is as high as 3.59×10 15 Jones and the gain-bandwidth product reaches 1.45GHz, reflecting the excellent performance of the photodetector.

[0045] In summary, the MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect prepared in the present invention has excellent characteristics such as high responsiveness, high response speed and good stability.

[0046] Example 2

[0047] The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect provided in this embodiment is basically consistent with the structure and preparation method of Example 1, with the only difference being that in step b of Example 1, during the formation of a shallow thin film in the silicon channel, the thickness of the MXene layer is adjusted by adjusting the tightness between the mask and the single crystal silicon, so that the thickness of the MXene layer in the channel is about 0.1 μm.

[0048] Example 3

[0049] The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect provided in this embodiment is basically consistent with the structure and preparation method of Embodiment 1, with the only difference being that in step b of Embodiment 1, during the formation of a shallow thin film in a silicon channel, the thickness of the MXene layer is adjusted by adjusting the tightness between the mask and the single crystal silicon, so that there is no MXene layer in the channel.

[0050] Example 4

[0051] The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect provided in this embodiment is basically consistent with the structure and preparation method of embodiment 1, with the only difference being that in step b of embodiment 1, during the formation of the shallow thin film in the silicon channel, the thickness of the MXene layer is adjusted by adjusting the tightness between the mask and the single crystal silicon, so that the thickness of the MXene layer in the channel is the same as the thickness of the electrode part and the functional part.

[0052] like Fig.10 As shown in the figure, the light response curves of the photodetectors of Examples 1, 2, 3, and 4 under -1V bias voltage and 850nm light illumination (light intensity is 1.1mW / cm 2 ). It can be seen that when there is a small amount of MXene thin layer in the channel, the light response will increase rapidly; when there is no thin layer in the channel or it is filled with thin layers, the light response will decrease rapidly.

[0053] The above description is only an exemplary embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect, characterized in that: The photodetector is based on a single crystal silicon (1) substrate, and a pair of patterned MXene films arranged at intervals are formed on the surface of the substrate; the structure of each patterned MXene film includes an electrode portion (2) and a functional portion (3) extending from one side of the electrode portion toward another patterned MXene film in an integrated manner; the interval between the functional portions of the two patterned MXene films forms a channel, and the two functional portions and the silicon in the channel form a MXene-Si-MXene van der Waals structure; a MXene thin layer (4) is arranged in the channel to form a synergistic light trapping effect.

2. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 1, characterized in that: The thickness of the substrate is 100 μm-500 μm.

3. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 1, characterized in that: The thickness of the patterned MXene film is 1 μm to 5 μm.

4. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 1, characterized in that: The electrode part (2) is square in shape, with a side length of 1500 to 2000 μm.

5. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 1, characterized in that: The functional part (3) is rectangular, 700 to 1000 μm long and 150 to 200 μm wide.

6. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 1, characterized in that: The channel between the two functional parts is 700 to 1000 μm long and 50 to 100 μm wide.

7. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 1, characterized in that: The thickness of the MXene thin layer is 0.1 to 0.3 μm.

8. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 1, characterized in that: The method for preparing the patterned MXene film is as follows: a mask matching the structure of the patterned MXene film is provided, the mask is fixed on top of a substrate, a solution of a MXene material is dripped onto the substrate using the mask, and a patterned MXene film is formed after drying; at the same time, the dripped solution diffuses into the channel between the functional parts of the two patterned MXene films to form a MXene thin layer.

9. The MXene-Si-MXene van der Waals photodetector with synergistic light trapping effect according to claim 8, characterized in that: By controlling the degree of clamping between the mask and the substrate, the diffusion of the solution in the channel is controlled, thereby controlling the thickness of the MXene layer.

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