A synergistic light-trapping effect of MXene-si-MXene van der waals photodetector

Abstract

The application discloses a kind of MXene-Si-MXene van der Waals photoelectric detectors of synergic light trapping effect, it is with single crystal silicon as substrate, there is a pair of interval setting patterned MXene film on the surface of substrate;The structure of each patterned MXene film includes an electrode part, and the functional part that is integratedly extended from the side of electrode part towards another patterned MXene film;The interval between the functional part of two patterned MXene films forms channel, and the silicon in two functional parts and channel constitutes MXene-Si-MXene van der Waals structure;MXene thin layer is arranged in channel to form synergic light trapping effect.The detector prepared in the application has the advantages of large responsivity, fast response speed, good stability, high detection rate, and also has the advantages of easy preparation, low cost, etc.

Description

Technical Field

[0001] This invention relates to a synergistic light-trapping effect MXene-Si-MXene van der Waals photodetector, belonging to the field of semiconductor optoelectronic device technology. Background Technology

[0002] Photodetectors have a wide range of applications in daily life, such as environmental monitoring, medical imaging, optical communication, security inspection, and life sciences. However, increasingly complex application environments are placing higher demands on 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 often conflicting and cannot be simultaneously achieved. Avalanche photodiodes (APDs) achieve high GBP, but their complex structure and relatively high cost still present significant obstacles and complex manufacturing processes. Common metal-semiconductor-metal (MSM) photodiodes are attractive in terms of bandwidth requirements due to their ease of fabrication, but they still face limitations in achieving high sensitivity. To improve sensitivity, various physical mechanisms, such as optical gating, have been introduced to significantly increase gain, but these have not met the high bandwidth requirements. Therefore, developing a low-cost, simple photodetector that simultaneously satisfies both high gain and high bandwidth is of great significance.

[0004] MXenes, as a class of promising two-dimensional materials, possess excellent metallic conductivity, biocompatibility, large specific surface area, and rich surface chemical properties, making them highly valuable in optical and electronic devices. The article "MXene-GaN van der Waals metal-semiconductor junctions for high-performance multiple quantum well photodetectors" further explores this topic. [1] The paper discloses that MXene has excellent optical and electrical properties such as tunable work function, high transmittance, high conductivity, no dangling bonds on the surface, and electrode fabrication can be achieved through van der Waals (vdW) contacts. It is expected to solve the important problem of the difficulty in improving the performance of traditional photodetectors, such as the barrier height. However, it still has problems such as low responsivity, low detectivity and small bandwidth, which limit its application.

[0005] Therefore, the MXene-Si-MXene van der Waals photodetector, which combines the MSM structure and utilizes the optical gating mechanism to fabricate a synergistic light-trapping effect, 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] To address the shortcomings and deficiencies of the existing technologies, this invention provides a synergistic light-trapping effect MXene-Si-MXene van der Waals photodetector, aiming to obtain a low-cost, high-gain-bandwidth product photodetector.

[0009] To solve the technical problem, the present invention adopts the following technical solution:

[0010] A synergistic light-trapping MXene-Si-MXene van der Waals photodetector is characterized in that: the photodetector uses single-crystal silicon as a substrate, and a pair of spaced-apart patterned MXene thin films are formed on the substrate surface; each patterned MXene thin film includes an electrode portion and a functional portion integrally extended from one side of the electrode portion toward the other patterned MXene thin film; the gap between the functional portions of the two patterned MXene thin films forms a channel, and the two functional portions and the silicon in the channel constitute an MXene-Si-MXene van der Waals structure; an MXene thin layer is disposed in the channel to form a synergistic light-trapping effect.

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

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

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

[0014] The thickness of the MXene thin layer is 0.1–0.3 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 up, the mask is fixed above the substrate, a solution of MXene material is dropped onto the substrate using the mask, and after drying, a patterned MXene film is formed; at the same time, the dropped solution diffuses into the channel between the functional parts of the two patterned MXene films to form an MXene thin layer.

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

[0017] Compared with existing technologies, the beneficial effects of this invention are reflected in:

[0018] The photodetector prepared by this invention has high sensitivity, high Schottky barrier height, fast response speed, and high detectivity. At the same time, the preparation method of the photodetector of this invention has the advantages of being simple, highly compatible, highly stable, and easy to prepare large-area devices. It has broad application prospects in the development of low-cost, high-speed, stable, and highly integrated detectors. Attached Figure Description

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

[0020] Figure 2 This is a schematic diagram of the mask used to prepare the patterned MXene thin film in Example 1, where the left image corresponds to the patterned mask and the right image corresponds to the substrate mask.

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

[0022] Figure 4 This is a normalized magnified schematic diagram of a single optical response period of the photodetector in Example 1 at 0.2 kHz and the Schottky photodetector at 22 kHz.

[0023] Figure 5 The image shows the normalized photovoltage curve of a single response period for the photodetector of Example 1 at a pulsed light frequency of 200 kHz.

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

[0025] Figure 7 The curves showing the response of the photodetector of Example 1 to different light intensities over time under a bias voltage of -1V and illumination of 850nm are shown.

[0026] Figure 8 The curves showing the dependence of light intensity on photocurrent for the photodetector of Example 1 under bias voltages of -1V and 2V and illumination of 850nm are shown.

[0027] Figure 9 The detectivity and gain-bandwidth product of the photodetector in Example 1 under a bias voltage of 2V and under 850nm illumination of different light intensities.

[0028] Figure 10 The graphs show the changes in photoresponse over time for the photodetectors in Examples 1, 2, 3, and 4 under a bias voltage of -1V and illumination of 850nm. Detailed Implementation

[0029] The embodiments of the present invention are described in detail below. These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. However, the scope of protection of the present invention is not limited to the following embodiments.

[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 single-crystal silicon 1 as a substrate, and forms a pair of patterned MXene thin films spaced apart on the substrate surface; each patterned MXene thin film includes an electrode portion 2 and a functional portion 3 integrally extending from one side of the electrode portion toward the other patterned MXene thin film; the gap between the functional portions of the two patterned MXene thin films forms a channel, and the two functional portions and the silicon in the channel constitute an MXene-Si-MXene van der Waals structure; an MXene thin layer 4 is disposed 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 formed patterned MXene thin film is Ti3C2T. xThe MXene film is 3 μm thick. The electrode portion is square with a side length of 2000 μm. The functional portion is rectangular, 1000 μm long and 200 μm wide, with the shorter side of the "width" of the functional portion located on one side of the electrode portion. The channel between the two functional portions is 1000 μm long and 100 μm wide. The length direction of the channel is the same as the length of the functional portion (therefore, it is equal to the length of the functional portion), and the width direction is the same as the short side of the functional portion. The thickness of the MXene layer within the silicon channel is 0.2 μm.

[0033] The method for fabricating the photodetector in this embodiment includes the following steps:

[0034] a. Clean the 10*10mm single-crystal Si crystal sequentially in acetone, ethanol, and deionized water for 5 minutes each to remove organic matter from the surface.

[0035] b. Take as Figure 2 The mask shown comprises a patterned plate and a substrate. Monocrystalline silicon is placed between the two, and then the patterned plate and substrate are secured using threaded holes around their perimeter, clamping the monocrystalline silicon in place. Ti3C2T is then deposited onto the substrate through the patterned vias in the patterned plate. x The solution of MXene material is then transferred to a 60°C drying stage to form a patterned MXene film. Simultaneously, the added solution diffuses into the channel between the functional parts of the two patterned MXene films to form an MXene thin layer, thus creating a synergistic light-trapping MXene-Si-MXene van der Waals photodetector, denoted as SPE-PD.

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

[0037] For comparison, this embodiment also prepares a conventional Schottky structure photodetector: MXene material is coated onto bare silicon and dried to serve as a Schottky contact electrode, while an In / Ga paste silicon wafer is coated onto a substrate to serve as an ohmic contact electrode. The MXene thin film and the silicon substrate form a Schottky junction.

[0038] Figure 3 The figures show the responsivity (R) and external quantum efficiency (EQE) curves of the photodetector in Example 1 under different wavelengths of illumination with a bias voltage of -1V. The peak responsivity reaches 125.6 A / W at 850 nm, corresponding to an EQE of 2 × 10⁻⁶. 4 %.

[0039] Figure 4The diagram shows the normalized magnified 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 image shows the normalized photovoltage curve for a single response cycle of the photodetector in Example 1 at a pulsed light frequency of 200 kHz. The calculated rise / fall times are 0.6 / 1.8 μs, indicating a high response speed.

[0041] Figure 6 The bandwidth and responsivity of the photodetector in Example 1 are compared with those of commercial avalanche detectors and other previously reported Schottky photodiodes. 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 Compared to APhys., vol. 291, pp. 87-92, 2019 / 06 / 01 / 2019, doi:10.1016 / j.sna.2019.03.054., the photodetector of this invention exhibits a bandwidth of up to 200 kHz, far exceeding other diodes. Compared to Thorlabs APDs (specifically, the APD440A), the bandwidth of the photodetector of this invention exceeds that of some models, and its responsivity at low bias voltage far surpasses that of most current models.

[0042] Figure 7The image shows the response curves of the photodetector of Example 1 under different light intensities with time under a bias voltage of -1V and illumination of 850nm. The measurement results show that the device has a stable current switching ratio.

[0043] Figure 8 The graph shows the dependence of light intensity on photocurrent for the photodetector of Example 1 under bias voltages of -1V and 2V and illumination at 850nm. It is evident from the graph that the incident light intensity and the corresponding photocurrent value exhibit a good linear relationship.

[0044] Figure 9 The detectivity and gain-bandwidth product of the photodetector in Example 1 are shown under a bias voltage of 2V and under 850nm illumination of different intensities. Under a bias voltage of 2V, the photodetector achieves a detectivity as high as 3.59 × 10⁻⁶. 15 Jones and its gain-bandwidth product reaches 1.45 GHz, demonstrating the excellent performance of the photodetector.

[0045] In summary, the MXene-Si-MXene van der Waals photodetector with synergistic light-trapping effect prepared in this invention has excellent characteristics such as high responsivity, 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 the same as the structure and preparation method in Example 1. The only difference is that in step b of Example 1, during the formation of the shallow thin film in the silicon channel, the thickness of the MXene thin film is adjusted by adjusting the tightness between the mask and the single crystal silicon, so that the thickness of the MXene thin film 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 the same as the structure and preparation method in Embodiment 1. The only difference is that in step b of Embodiment 1, during the formation of a shallow thin film in the silicon channel, the thickness of the MXene thin film is adjusted by adjusting the tightness between the mask and the single crystal silicon, so that there is no MXene thin film 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 the same as the structure and preparation method in Embodiment 1. The only difference is that in step b of Embodiment 1, during the formation of the shallow thin film in the silicon channel, the thickness of the MXene thin layer is adjusted by adjusting the tightness between the mask and the single crystal silicon, so that the thickness of the MXene thin layer in the channel is the same as the thickness of the electrode part and the functional part.

[0052] like Figure 10 As shown, the photoresponse curves of the photodetectors in Examples 1, 2, 3, and 4 under a bias voltage of -1V and illumination of 850nm light (light intensity 1.1mW / cm²) change over time. 2 It can be seen that when a small amount of MXene thin layer is present in the channel, the photoresponse increases rapidly; when there is no thin layer in the channel or the channel is completely filled with a thin layer, the photoresponse decreases rapidly.

[0053] The above description is merely 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 within the protection scope of the present invention.

Claims

1. A synergistic light-trapping effect MXene-Si-MXene van der Waals photodetector, characterized in that: The photoelectric detector is a single crystal silicon (1) as a substrate, and a pair of spaced patterned MXene films are formed on the surface of the substrate; the structure of each patterned MXene film includes an electrode part (2), and a functional part (3) integrated extending from one side of the electrode part to the other patterned MXene film; the gap between the functional parts of the two patterned MXene films forms a channel, and the two functional parts 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; the thickness of the patterned MXene film is 1-5 μm; the thickness of the MXene thin layer is 0.1-0.3 μm.

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

3. The synergistic light-trapping MXene-Si-MXene van der Waals photodetector according to claim 1, wherein: The electrode part (2) is square, and the side length is 1500-2000 μm.

4. The synergistic light-trapping MXene-Si-MXene van der Waals photodetector according to claim 1, wherein: The functional part (3) is rectangular, and the length is 700-1000 μm, and the width is 150-200 μm.

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

6. The synergistic light-trapping MXene-Si-MXene van der Waals photodetector of claim 1, wherein, The preparation method of the patterned MXene film is as follows: a mask plate matched with the structure of the patterned MXene film is arranged, the mask plate is fixed above the substrate, MXene material solution is dropped on the substrate by using the mask plate, and the patterned MXene film is formed after drying; at the same time, the dropped solution diffuses into the channel between the functional parts of the two patterned MXene films to form a MXene thin layer.

7. The synergistic light-trapping MXene-Si-MXene van der Waals photodetector according to claim 6, wherein: The thickness of the MXene thin layer is controlled by controlling the clamping degree of the mask plate and the substrate and the diffusion of the solution in the channel.

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