Construction method of graphene near-infrared detector with GaAs substrate and detector

Abstract

The invention discloses a construction method of a graphene near-infrared detector with a GaAs substrate and the detector. Silvaco Tcad and Lumeral FDTD are used for constructing an equivalent structure model of the optical detector, and the optical performance and the electrical performance of the optical detector are analyzed; an optical detector equivalent structure model comprises a p-type graphene heterojunction and an n-type GaAs substrate, the graphene heterojunction is formed by stacking graphene, InSb and AlSb, and the thickness and doping concentration of each layer of the graphene heterojunction are accurately controlled to form a unique graphene heterojunction, so that the pn-type photoelectric detector with excellent optical response performance is constructed. According to the detector, generation of photon-generated carriers can be accelerated under the action of a built-in electric field, recombination is reduced, and the light responsivity of the detector is improved; meanwhile, hot electrons excited in the InSb dielectric layer can cross an interface barrier to be injected into the graphene, and rapid response is achieved through ballistic transport of the graphene.

Description

Technical Field

[0001] The present invention relates to the technical field of near-infrared photoelectric detectors, and more particularly to a construction method of a graphene near-infrared detector based on a GaAs substrate and the detector. Background Art

[0002] In recent years, with the rapid development of technologies such as autonomous driving, smart agriculture, and smart homes, traditional photodetectors have faced bottlenecks in terms of lightweighting and flexibility. Graphene, with its advantages such as zero-gap band structure and high carrier mobility, has become a research hotspot. However, graphene's light absorption capacity is very limited, and its carrier recombination lifetime is short, making it difficult to achieve high responsiveness in the prepared photodetectors. This shortcoming can be effectively compensated by constructing a graphene heterojunction. Graphene heterojunctions combine the excellent physical and chemical properties of two or more materials, resulting in photoelectric properties that are far superior to those of individual semiconductors. This is crucial for the development of high-performance photodetectors and has broad prospects in areas such as the Internet of Things and wearable devices.

[0003] Therefore, how to provide a method for constructing a graphene near-infrared detector based on a GaAs substrate and a detector is an urgent problem that those skilled in the art need to solve. Summary of the Invention

[0004] In view of this, the present invention provides a method for constructing a graphene near-infrared detector on a GaAs substrate and the detector. By accurately controlling the thickness and doping concentration of each layer of the graphene heterojunction, a unique graphene heterojunction is formed, thereby constructing a pn-type photodetector with excellent light response performance. The built-in electric field of this detector can accelerate the generation of photogenerated carriers, reduce recombination, and improve its light response. At the same time, hot electrons excited in the InSb dielectric layer can cross the interface potential barrier and be injected into the graphene, achieving rapid response through ballistic transport of the graphene.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for constructing a graphene near-infrared detector on a GaAs substrate, comprising:

[0007] Based on the actual physical parameters of the photodetector, the equivalent structure model of the photodetector is constructed through Lumerical FDTD, and the optical characteristics of the photodetector are simulated;

[0008] Based on the equivalent structural model of the photodetector, an electrical model was constructed using Silvaco Tcad to simulate the actual operation process of the photodetector.

[0009] Preferably, the photodetector equivalent structure model includes a graphene heterojunction and a GaAs substrate, and the graphene heterojunction is located on top of the GaAs substrate.

[0010] Preferably, the GaAs substrate has a thickness of h1, a length and a width of d1; h1 = 1 μm, d1 = 4 μm;

[0011] Graphene heterojunctions include:

[0012] The AlSb buffer layer at the bottom has a thickness of h2 and a length and width of d1; h2 = 1 μm;

[0013] The InSb dielectric layer embedded in the AlSb buffer layer has a thickness of h3, a length of d2, and a width of d1; h3 = 0.5 μm, d2 = 2 μm;

[0014] The graphene layer located on the surface has a thickness of h4, and a length and width of d1; h4 = 0.005 μm.

[0015] Preferably, the photodetector is a pn-type photodetector. When simulating it through Silvaco Tcad, the graphene heterojunction is p-type doped and the GaAs substrate is n-type doped, wherein the graphene layer serves as the anode and the bottom of the GaAs substrate serves as the cathode.

[0016] Preferably, the graphene layer is p-type doped with a doping concentration of 1×10 20 ;

[0017] The InSb dielectric layer is p-type doped with a doping concentration of 2×10 19 ;

[0018] The AlSb buffer layer was p-type doped with a doping concentration of 5×10 18 ;

[0019] The GaAs substrate is n-doped with a doping concentration of 4×10 19 .

[0020] Preferably, when simulating the actual operation process of the photodetector by Silvaco Tcad, the negative electrode of the DC power supply is connected to the anode, the positive electrode is connected to the cathode, and a reverse voltage is applied to the anode and a forward voltage is applied to the cathode to form a closed loop.

[0021] Preferably, when simulating the actual operation of the photodetector by Silvaco Tcad, add plane light incident vertically on the top of the photodetector equivalent structure model, and specify the incident wavelength to be 0.2μm-1.4μm and the optical power to be 1W / cm 2 .

[0022] Preferably, when simulating the optical characteristics of the photodetector by LumericalFDTD, plane light incident vertically on the top is added to the equivalent structure model of the photodetector, and the incident wavelength is specified to be 0.2 μm-1.4 μm.

[0023] A graphene near-infrared detector on a GaAs substrate is obtained by the above construction method.

[0024] It can be seen from the above technical solution that compared with the prior art, the present invention discloses a method for constructing a graphene near-infrared detector on a GaAs substrate and a detector, by rationally stacking and doping graphene with AlSb and InSb materials to construct a p-type heterojunction, so that it has a certain degree of light absorption while retaining high mobility.

[0025] The hot electrons excited in the InSb dielectric layer can cross the interface barrier and be injected into graphene, achieving rapid response through ballistic transport of graphene.

[0026] Lattice matching was taken into consideration when designing the structure, and AlSb also served as a buffer layer to better integrate the p-type heterojunction with the n-type GaAs substrate.

[0027] This structure has a high photoresponse peak in the entire 0.2-1.4μm near-infrared band, with the photoresponse reaching up to 0.329A / W, the external quantum efficiency reaching up to 66.9%, and the response time within 15ns. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0029] Figure 1 A flow chart of a method for constructing a graphene near-infrared detector based on a GaAs substrate provided by the present invention;

[0030] Figure 2 A three-dimensional diagram of the equivalent structural model of the photoelectric detector provided by the present invention;

[0031] Figure 3 A front view of the equivalent structural model of the photoelectric detector provided by the present invention;

[0032] Figure 4 is a schematic diagram of the absorption spectrum of the photodetector in the present invention;

[0033] Figure 5Schematic diagram of the external quantum efficiency of the photodetector in the present invention;

[0034] Figure 6 Schematic diagram of the photoresponsivity of the photodetector in the present invention;

[0035] Figure 7 Add the rise time curve of the photocurrent in the light source to the photodetector of the present invention;

[0036] Figure 8 The falling time curve of the photocurrent when the light source is removed from the photodetector of the present invention;

[0037] Figure 9 The electric field distribution at 0.82 μm in the xy plane where the photodetector of the present invention is located;

[0038] Figure 10 The magnetic field distribution at 0.82 μm in the xy plane where the photodetector in the present invention is located is shown in FIG. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] The embodiment of the present invention discloses a method for constructing a graphene near-infrared detector on a GaAs substrate, such as Figure 1 Shown, including:

[0041] Based on the actual physical parameters of the photodetector, the equivalent structure model of the photodetector is constructed through LumericalFDTD, and the optical characteristics of the photodetector are simulated;

[0042] Based on the equivalent structural model of the photodetector, an electrical model was constructed using Silvaco Tcad to simulate the actual operation process of the photodetector.

[0043] In the LumericalFDTD simulation settings, vertical plane wave incidence is adopted, the polarization direction of the electromagnetic wave is set to the x direction, the wavelength range of the solution is set to 0.2-1.4μm, the electric field direction of the electromagnetic wave is along the negative direction of the y axis, the magnetic field direction is along the negative direction of the x axis, and the wave vector is along the negative direction of the z axis. In order to simulate a single periodic structure, the boundary conditions of the x, y and z axes are all set to PML (Perfectly Matched Layer) perfect absorption boundary conditions to effectively absorb the reflection and radiation of the incident wave. In the Silvaco Tcad simulation settings, vertical plane wave incidence is also adopted. Compared with the light source set by the Lumerical FDTD simulation model, it is also necessary to specify the incident light power of the light source as 1W / cm 2 , and apply a voltage of -5V to the anode and a voltage of 0V to the cathode, so that the anode is reverse biased and the cathode is forward biased.

[0044] like Figure 2 and Figure 3 As shown, the equivalent structural model of the photodetector includes a graphene heterojunction and a GaAs substrate 1. The graphene heterojunction is located on top of the GaAs substrate 1, which is an n-type GaAs substrate. A p-type graphene heterojunction absorption part is stacked on top. The p-type graphene heterojunction includes: an AlSb buffer layer 2 located at the bottom, an InSb dielectric layer 3 embedded in the AlSb buffer layer 2, and a graphene layer 4 located at the surface. The graphene layer 4 serves as an anode, and the bottom of the GaAs substrate 1 serves as a cathode. A reverse bias is applied to the anode, and a forward bias is applied to the cathode.

[0045] Furthermore, a GaAs substrate 1 has a thickness of h1 and a length and width of d1; h1 = 1 μm, d1 = 4 μm;

[0046] AlSb buffer layer 2, thickness h2, length and width d1; h2 = 1 μm;

[0047] InSb dielectric layer 3, thickness h3, length d2, width d1; h3 = 0.5 μm, d2 = 2 μm;

[0048] The graphene layer 4 has a thickness of h4 and a length and width of d1; h4 = 0.005 μm.

[0049] In order to better regulate the built-in electric field of the photodetector, reduce carrier recombination, and drive its directional movement, the graphene heterojunction absorption structure is p-type doped and the GaAs substrate is n-type doped. That is, the four materials of graphene, AlSb, InSb, and GaAs need to be doped. The graphene layer 4 is p-type doped with a doping concentration of 1×10 20 ; The InSb dielectric layer 3 is p-type doped with a doping concentration of 2×1019 ; The AlSb buffer layer 2 is p-type doped with a doping concentration of 5×10 18 ; GaAs substrate 1 is n-type doped with a doping concentration of 4×10 19 .

[0050] Based on the above construction method, the present invention obtains a high-response pn-type near-infrared photodetector based on graphene heterojunction, which covers the key frequency bands of the near-infrared spectral region.

[0051] like Figure 4 Figure 2 shows the absorption distribution of this photodetector in the 0.2-1.4μm near-infrared band. Graphene itself has an extremely low light absorption rate of less than 3%. However, when combined with other semiconductor materials to form a heterojunction, its absorption properties are greatly improved, enabling it to achieve high mobility while also providing excellent spectral response, thus promising a wide range of applications in the field of near-infrared photodetectors.

[0052] like Figure 5 As shown, the external quantum efficiency distribution of the photodetector in the 0.2-1.4μm near-infrared band is a major performance indicator of the photodetector, reflecting its ability to convert incident light signals into effective electrical signals. It also reflects the sensitivity of the photodetector to incident light of different wavelengths and can be used to indicate whether the photodetector matches the incident light source. The external quantum efficiency of the photodetector of the present invention in this band can reach up to 66.9%.

[0053] like Figure 6 As shown, the photoresponsivity distribution of the photodetector in the 0.2-1.4μm near-infrared band is a key parameter for measuring the conversion of incident light power into electrical signal intensity, and is also the most important indicator in photodetector research. The photoresponse of the photodetector of the present invention in this band can reach up to 0.329A / W.

[0054] Photodetectors also have a very important indicator, the light response time, which determines the detector's ability to track rapidly changing light signals. Figure 7 , in dark conditions, a 5V reverse bias is applied to the photodetector and 1W / cm 2 The time required for the photocurrent to increase from 0 to a stable state when the light source is on. Figure 8 The rise and fall times of the photodetector are both within 15ns, indicating that the photodetector has both high light responsivity and extremely high response speed.

[0055] In order to observe the electromagnetic field distribution inside the light detector when a plane wave is incident on the surface, a simulation is performed in LumericalFDTD. Figure 9 and 10 It can be seen from the figure that when the photoresponsivity reaches its peak, the incident wavelength is 0.82μm, and the incident light excites the surface plasmon of graphene, so that the electric field is localized near the graphene layer; while the magnetic field is mainly distributed on the upper part and both sides of the InSb dielectric layer, indicating that the absorption of the graphene heterojunction is mainly due to the mutual coupling of the localized surface plasmon resonance excited by the InSb dielectric layer and the transmission surface plasmon resonance.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0057] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for constructing a graphene near-infrared detector on a GaAs substrate, characterized in that: include: Based on the actual physical parameters of the photodetector, the equivalent structure model of the photodetector is constructed through Lumerical FDTD, and the optical characteristics of the photodetector are simulated; Based on the equivalent structural model of the photodetector, an electrical model was constructed using Silvaco Tcad to simulate the actual operation process of the photodetector.

2. The method for constructing a graphene near-infrared detector based on a GaAs substrate according to claim 1, wherein: The photodetector equivalent structure model includes a graphene heterojunction and a GaAs substrate, where the graphene heterojunction is located on top of the GaAs substrate.

3. The method for constructing a graphene near-infrared detector based on a GaAs substrate according to claim 2, wherein: GaAs substrate, thickness h1, length and width d1; h1 = 1 μm, d1 = 4 μm; Graphene heterojunctions include: The AlSb buffer layer at the bottom has a thickness of h2 and a length and width of d1; h2 = 1 μm; The InSb dielectric layer embedded in the AlSb buffer layer has a thickness of h3, a length of d2, and a width of d1; h3 = 0.5 μm, d2 = 2 μm; The graphene layer located on the surface has a thickness of h4, and a length and width of d1; h4 = 0.005 μm.

4. The method for constructing a graphene near-infrared detector based on a GaAs substrate according to claim 3, wherein: The photodetector is a pn-type photodetector. When it is simulated by Silvaco Tcad, the graphene heterojunction is p-type doped and the GaAs substrate is n-type doped, wherein the graphene layer serves as the anode and the bottom of the GaAs substrate serves as the cathode.

5. The method for constructing a graphene near-infrared detector based on a GaAs substrate according to claim 4, characterized in that: The graphene layer is p-type doped with a doping concentration of 1×10 20 ; The InSb dielectric layer is p-type doped with a doping concentration of 2×10 19 ; The AlSb buffer layer was p-type doped with a doping concentration of 5×10 18 ; The GaAs substrate is n-doped with a doping concentration of 4×10 19 .

6. The method for constructing a graphene near-infrared detector based on a GaAs substrate according to claim 4, characterized in that: When simulating the actual operation of a photodetector using Silvaco Tcad, the negative pole of a DC power supply is connected to the anode, the positive pole is connected to the cathode, a reverse voltage is applied to the anode, and a forward voltage is applied to the cathode to form a closed loop.

7. The method for constructing a graphene near-infrared detector based on a GaAs substrate according to claim 1, characterized in that: When simulating the actual operation of the photodetector using Silvaco Tcad, a plane light incident vertically on the top of the photodetector is added to the equivalent structure model, and the incident wavelength is specified to be 0.2μm-1.4μm and the optical power is 1W / cm 2 .

8. The method for constructing a graphene near-infrared detector based on a GaAs substrate according to claim 1, wherein: When simulating the optical properties of a photodetector using Lumerical FDTD, add plane light incident vertically on the top of the photodetector equivalent structure model, and specify its incident wavelength as 0.2μm-1.4μm.

9. A graphene near-infrared detector based on a GaAs substrate, characterized in that: Obtained according to the construction method according to any one of claims 1 to 8.

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