Fractal gold nano-film modified graphene near-infrared photoconductive detector
By depositing fractal gold nanofilms on the surface of graphene and utilizing surface plasmon resonance coupled with the electric field of graphene, the problem of low light absorption rate of graphene photodetectors was solved, and efficient near-infrared photodetection was achieved.
Patent Information
- Application Number
- CN202421090667.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-20
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2034-05-20
AI Technical Summary
Graphene photodetectors have low light absorption rates, which makes them unable to effectively detect light signals. Furthermore, existing methods to improve light absorption require complex micro-nano fabrication techniques, resulting in high device fabrication costs and low yields.
Fractal gold nanofilms are deposited on the surface of graphene. By using surface plasmon resonance to couple with the electric field of graphene, photogenerated carriers are injected into the lower graphene layer, forming a potential difference and transporting it to the external circuit, thus realizing high-performance photoelectric detection.
With a light absorption rate exceeding 40% in the 1200-1800 nm wavelength range and a near-infrared photoelectric response of up to 20 mV/W, the photoelectric detection performance is significantly improved.
Smart Images
Figure CN223899583U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model belongs to photoelectric sensing technical field, concretely relates to a fractal gold nanometer film modified graphene near infrared photoconductive type detector. BACKGROUND
[0002] Graphene has attracted much attention due to its unique properties, such as zero band gap, wide spectral response, ultra-high carrier mobility, short relaxation time, and electrostatic doping tuning. It is considered as an ideal new type of photodetector material. As a zero band gap two-dimensional material, it can realize the detection of ultra-wide band spectrum from terahertz waveband to mid-infrared waveband. In addition, its two-dimensional characteristics also allow compatible integration with photonic integrated circuits. In traditional graphene photoconductive type detectors based on field effect transistors (FET), the lifetime of photo-induced carriers is extremely short (sub-picosecond time scale) and the light absorption is low, resulting in low responsivity. In order to prolong the lifetime of photo-induced carriers, some researchers have proposed a method of introducing quantum dots into graphene to create trapping centers. Using hybrid graphene / quantum dot structures or graphene quantum dot (GQD) array photodetectors, higher photoconductive gain and responsivity can be achieved. In addition, by introducing a built-in electric field to prolong the recombination time of carriers, graphene double-layer heterostructure can also improve the responsivity. However, due to light trapping effect, the light response time of the device is usually limited to hundreds of milliseconds or even tens of seconds. In recent years, some researchers have also reported hybrid graphene-semiconductor photodetectors, such as perovskite, silicon, and Bi2Te3. Although these devices have excellent responsivity, their light absorption depends on the semiconductor rather than graphene, thus limiting their spectral detection range.
[0003] In 2013, Zhang et al. reported a study on a pure monolayer graphene photodetector. By introducing electron traps and creating a band structure that opens a band gap in graphene, the research team made significant progress. The pure monolayer graphene photodetector has a high photoresponsivity of 8.61 A / W, which is about three orders of magnitude higher than previously reported. In addition, experiments have demonstrated that the device has a wideband high photoresponsivity in the visible to mid-infrared range. This work not only proves that the pure monolayer graphene photodetector has the widest light response capability, but also highlights graphene as a highly potential efficient optoelectronic device material, providing valuable insights for promoting research and development in the field of optoelectronic devices. In 2020, Wei et al. proposed a metasurface-mediated graphene photodetector with cascaded polarization-sensitive light response under uniform illumination. This work simulates an artificial bulk photovoltaic effect (BPVE). With the assistance of non-centrosymmetric metal nanoantennas, hot carriers in graphene are excited and gain momentum, forming a non-local and directional displacement current. Then, they demonstrate a zero-bias, non-cooled mid-infrared photodetector with a response rate three orders of magnitude higher than traditional BPVE, and a noise equivalent power of 0.12 nW / Hz 1 / 2 . In addition, they also observed the phenomenon of vector light response, which enables the detector to detect the polarization angle of the incident light. In 2021, Ming Ye et al. reported a study on a graphene photogalvanic detector. They successfully achieved polarization-independent and fast response characteristics by integrating a type of plasmonic nanoantenna called Jerusalem cross antenna (JC-antenna). Compared with previous work, the JC antenna can more effectively focus the incident light on graphene and enhance the polarization-independent light absorption effect. At room temperature and low temperature conditions, the photogalvanic detector has a response of 14.5 V / W (room temperature) and 4400 V / W (78 K), respectively. Due to the carrier collection of the JC antenna and the gapless band structure of graphene, the detector also exhibits significant broadband light response, covering the visible and near-infrared bands. In addition, the detector has a fast time response, with a measured rise time of 3 ns, which is sufficient to meet the needs of many practical applications (such as imaging technology). In 2022, Jiang et al. reported a single-layer graphene photodetector based on a silicon grating structure, which can significantly enhance the photovoltaic effect by establishing an internal potential through a potential fluctuation engineering mechanism. The enhancement factor of the device response rate is related to a newly defined parameter, the fluctuation period rate (P f ). Compared with devices without nanostructured substrates, devices with optimized P f have a 100-fold increase in response rate, with a response rate of 240 A / W at 1550 nm wavelength and room temperature, and a detection rate D* of 3.4x10 12Jones. Utility model content
[0004] However, the ultra-low light absorption rate of graphene makes it unable to effectively detect optical signals. Although the light absorption can be improved and the performance of the photodetector can be improved through plasmonic resonance of micro / nano photonic structures, this usually requires complex micro / nano processing technology, resulting in high device preparation cost and low yield. Therefore, a fractal gold nanometer film modified graphene near-infrared photoconductive type detector is provided by depositing a fractal gold nanometer film on the surface of graphene to realize broadband plasmonic enhancement.
[0005] In order to solve the above-mentioned technical problems, the technical scheme provided by the present application is as follows:
[0006] The utility model provides a fractal gold nanometer film modified graphene near-infrared photoconductive type detector, including the bottom layer conductive electrode, silicon layer, insulating layer and top layer conductive electrode that set gradually, be equipped with bottom layer adhesive layer between bottom layer conductive electrode and silicon layer,
[0007] The top layer conductive electrode is covered on the insulating layer by two conductive electrodes, and a gap is provided between the two conductive electrodes; a top layer adhesive layer is provided between the top layer conductive electrode and the insulating layer.
[0008] A graphene layer is provided on the top of the top layer conductive electrode and the gap, and a fractal nanometer film is provided on the top of the graphene layer in the gap.
[0009] Preferably, the material of the insulating layer is silicon dioxide.
[0010] Preferably, the graphene layer is a copper-based single-layer graphene film, and the surface resistivity is 300-500 Ω / Sq, and the single-layer coverage rate is greater than 96%.
[0011] Preferably, the graphene layer is a single-layer graphene, and the thickness is 0.3-0.4 nm.
[0012] Preferably, the top layer conductive electrode and the bottom layer conductive electrode are both composed of 40 nm thick gold.
[0013] Preferably, the top layer adhesive layer and the bottom layer adhesive layer are both composed of chromium with a thickness of 5 nm.
[0014] Preferably, the fractal nanometer film is a gold nanometer film.
[0015] Preferably, the fractal nanometer film is obtained by metal plating film, and the thickness of the plating film is 10 nm.
[0016] Preferably, the fractal gold nanometer film modified graphene near-infrared photoconductive type detector has an optical absorption of more than 40% in the wavelength range of 1200-1800 nm.
[0017] Preferably, the fractal gold nanometer film modified graphene near-infrared photoconductive type detector has a highest near-infrared photoelectric response of 20 mV / W.
[0018] Compared with the prior art, the technical scheme of the utility model has the following advantages:
[0019] The fractal gold nanometer film modified graphene near-infrared photoconductive type detector has the surface plasmon resonance on the fractal gold nanometer film coupled with the electric field of graphene, photo-generated carriers are injected into the lower graphene, thereby changing the Fermi energy level of graphene, forming a potential difference between the graphene and the graphene not covered by the fractal gold nanometer film, and under the graphene super-high carrier mobility characteristics, the carriers are transported to an external circuit to form a current loop, thereby realizing the graphene near-infrared high-performance photoelectric detection. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 It is a fractal gold nanometer film modified graphene near-infrared photoconductive type detector model schematic diagram;
[0021] Figure 2 It is a fractal gold nanometer film modified graphene near-infrared photoconductive type detector AFM image and SEM image;
[0022] Figure 3 It is a fractal gold nanometer film modified graphene near-infrared photoconductive type detector scanning electron microscope image under different regions (a-c), planar electric field distribution diagram of different regions under the action of 1310 nm wavelength light (d-f), and cross-sectional electric field distribution diagram of the device at the same position under the action of 1310, 1450, 1550 nm wavelength light (g-i);
[0023] Figure 4 It is a fractal gold nanometer film modified graphene near-infrared photoconductive type detector planar electric field distribution diagram (a-c) and cross-sectional electric field distribution diagram (d-f) of the same region of the device under the action of 1320 nm wavelength light at different thicknesses of 5 nm, 10 nm and 15 nm;
[0024] Figure 5 It is a fractal gold nanometer film modified graphene near-infrared photoconductive type detector experimental and simulation absorption rate graph changing with wavelength;
[0025] Figure 6 It is a photoelectric current response (a) and responsivity (b) of a fractal gold nanometer film modified graphene near-infrared photoconductive type detector under the action of 1100-1600 nm wavelength light;
[0026] Figure 7A schematic diagram of a graphene near-infrared photoconductive detector modified with fractal gold nanofilm;
[0027] Explanation of reference numerals in the attached figures: 1-bottom conductive electrode, 2-insulating layer, 3-top conductive electrode, 4-graphene layer, 5-fractal nanofilm, 6-top adhesion layer, 7-silicon layer, 8-bottom adhesion layer. Detailed Implementation
[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.
[0029] Example 1
[0030] like Figure 1 As shown, a graphene near-infrared photoconductive detector modified with fractal gold nanofilm includes a bottom conductive electrode 1, a silicon layer 7, an insulating layer 2, and a top conductive electrode 3 arranged sequentially; a bottom adhesion layer 8 is provided between the bottom conductive electrode 1 and the silicon layer 7.
[0031] The insulating layer 2 is made of silicon dioxide.
[0032] The top conductive electrode 3 consists of two conductive electrodes symmetrically covering the insulating layer 2, with a gap between the two conductive electrodes; a top adhesive layer 6 is provided between the top conductive electrode 3 and the insulating layer 2.
[0033] Both the top conductive electrode 3 and the bottom conductive electrode 1 are composed of gold with a thickness of 40 nm. Both the top adhesion layer 6 and the bottom adhesion layer 8 are composed of chromium with a thickness of 5 nm.
[0034] A graphene layer 4 is provided on the top and gap of the top conductive electrode 3, and a fractal nanofilm 5 is provided on the top of the graphene layer 4 at the gap; the fractal nanofilm 5 is a gold nanofilm, which is obtained by coating, and the coating thickness is 10 nm.
[0035] The graphene layer 4 is a copper-based monolayer graphene film with a thickness of 0.3-0.4 nm, a surface resistivity of 300-500 Ω / Sq, and a monolayer coverage of more than 96%.
[0036] The graphene near-infrared photoconductive detector modified with fractal gold nanofilms exhibits light absorption exceeding 40% in the 1200–1800 nm wavelength range.
[0037] The graphene near-infrared photoconductive detector modified with fractal gold nanofilms exhibits a near-infrared photoresponse of up to 20 mV / W.
[0038] Example 2
[0039] The fractal gold nanofilm modified graphene near-infrared photoconductive detector comprises a conductive electrode, a silicon oxide insulating layer, single-layer graphene and fractal gold nanofilm.
[0040] Specifically, the conductive electrode, single-layer graphene and fractal gold nanofilm are sequentially arranged on the silicon oxide insulating layer.
[0041] Specifically, the single-layer graphene is connected to the conductive electrode.
[0042] Specifically, the fractal gold nanofilm covers the single-layer graphene.
[0043] The fractal gold nanofilm can absorb near-infrared light and excite surface plasmons to localize light on the gold surface. The surface plasmons transfer energy to valence electrons in the metal in a non-radiative decay manner, so that the valence electrons become hot carriers with high kinetic energy. By using the low state density characteristics of graphene, the photo-generated hot carriers generated by the continuous island-shaped gold film are injected into the lower graphene, so that the Fermi level of the graphene is increased, thereby causing the electric potential difference between the graphene with and without the continuous island-shaped gold film. The carriers in the graphene are driven by the different potentials to form a photocurrent. Thus, the device realizes near-infrared photoelectric response.
[0044] Effect evaluation 1
[0045] Figure 2 Atomic force microscope measurement shows that the film thickness is about 10 nm, and electron microscope images show that the fractal gold nanofilm structure is formed.
[0046] Figure 3 Figures (a-c) show SEM images of multiple regions of a single device. As can be clearly seen from the figures, when a 10 nm thick gold film is deposited, different nanostructure morphologies are formed on the surface of the device, and the structures present randomness in spatial position. From Figure 3 Figures (d-f) show that under the action of light with an incident wavelength of 1310 nm, the enhancement of electric field intensity is mainly concentrated in the tips and edges of the random gold islands. Figure 3 Figures (g-i) show the x-z cross-sectional electric field distribution of the same region of the device at three near-infrared wavelengths (1310 nm, 1450 nm and 1550 nm). The size, boundary and gap of the continuous island-shaped gold film are randomly distributed, so the plasmonic resonance has no obvious selectivity to the wavelength.
[0047] Figure 4 Figures (a-c) and (d-f) show the planar (x-y) and cross-sectional (x-z) electric field distribution of the same region of the device under the action of light with a wavelength of 1320 nm, when the thickness of the continuous island-shaped gold film is 5 nm, 10 nm and 15 nm, respectively. Figure 4 Figures (a-c) and (d-f) show the planar (x-y) and cross-sectional (x-z) electric field distribution of the same region of the device under the action of light with a wavelength of 1320 nm, when the thickness of the continuous island-shaped gold film is 5 nm, 10 nm and 15 nm, respectively. Figure 4(df). It can be concluded that as the thickness increases, the surface plasmon enhancement at the tip and edge of the continuous island structure also changes significantly.
[0048] Figure 5 Comparison of the optical absorption spectra obtained from experimental testing and simulation revealed that the two are quite consistent. The absorption rate of the device exceeds 40% in the wavelength range of 1200–1800 nm.
[0049] Figure 6 (a) compares the photocurrent responses of graphene photodetectors with and without continuous island gold film modification at different wavelengths under zero bias (a 4 μm diameter light spot completely covers the effective area of the device, concentrated on the non-central part of the continuous island gold film). It can be clearly observed that the graphene photodetector with continuous island gold film exhibits a significant photoelectric response in the wavelength range of 1100–1600 nm. In contrast, the photoelectric response of the pure graphene device is almost negligible. Figure 6 (b) shows that the graphene photoconductive device with continuous island gold film has a responsivity greater than 8 mV / W in the wavelength range of 1200–1600 nm, with the highest responsivity reaching 20 mV / W.
[0050] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.
Claims
1. A graphene near-infrared photoconductive detector modified with fractal gold nanofilm, characterized in that, It includes a bottom conductive electrode (1), a silicon layer (7), an insulating layer (2) and a top conductive electrode (3) arranged in sequence; a bottom adhesion layer (8) is provided between the bottom conductive electrode (1) and the silicon layer (7); The top conductive electrode (3) consists of two conductive electrodes symmetrically covering the surface of the insulating layer (2), with a gap between the two conductive electrodes; a top adhesive layer (6) is also provided between the top conductive electrode (3) and the insulating layer (2). The top conductive electrode (3) is provided with a graphene layer (4) at the top and gap, and a fractal nanofilm (5) is provided on the top of the graphene layer (4) at the gap; the fractal nanofilm (5) is a gold nanofilm, and the fractal nanofilm (5) is obtained by depositing a metal film with a thickness of 10 nm; the graphene near-infrared photoconductive detector modified by the fractal gold nanofilm has light absorption of more than 40% in the wavelength range of 1200-1800 nm.
2. The graphene near-infrared photoconductive detector modified with fractal gold nanofilm as described in claim 1, characterized in that, The insulating layer (2) is made of silicon dioxide.
3. The graphene near-infrared photoconductive detector modified with fractal gold nanofilm as described in claim 1, characterized in that, The graphene layer (4) is a copper-based monolayer graphene film with a surface resistivity of 300-500 Ω / Sq and a monolayer coverage of more than 96%.
4. The graphene near-infrared photoconductive detector modified with fractal gold nanofilm as described in claim 1, characterized in that, The thickness of the graphene layer (4) is 0.3-0.4 nm.
5. The graphene near-infrared photoconductive detector modified with fractal gold nanofilm as described in claim 1, characterized in that, Both the top conductive electrode (3) and the bottom conductive electrode (1) are composed of 40 nm thick gold.
6. The graphene near-infrared photoconductive detector modified with fractal gold nanofilm as described in claim 1, characterized in that, Both the top adhesive layer (6) and the bottom adhesive layer (8) are composed of chromium with a thickness of 5 nm.
7. The graphene near-infrared photoconductive detector modified with fractal gold nanofilm as described in claim 1, characterized in that, The fractal gold nanofilm-modified graphene near-infrared photoconductive detector exhibits a near-infrared photoresponse of up to 20 mV / W.