A visible light detector and a preparation method thereof

Abstract

The application discloses a visible light detector and a preparation method thereof. The structure of the visible light detector comprises InGaN nanorods grown on a silicon substrate, a first metal electrode located on the silicon substrate, a mixed solution of gold nanoparticles and PEDOT:PSS covering the surface of the InGaN nanorods, and a second metal electrode located on the InGaN nanorods covered with the mixed solution of gold nanoparticles and PEDOT:PSS. The introduction of PEDOT:PSS can effectively passivate the surface state of the InGaN nanorods and reduce the dark current. The introduction of gold nanoparticles can induce surface plasmon effect and improve the light response current. Compared with the detector without the mixed solution of gold nanoparticles and PEDOT:PSS, the detector has higher photoelectric current and lower dark current. The application has the advantages of low cost, excellent performance and simple preparation, and the visible light detector and the preparation method thereof can be applied to the field of visible light communication.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic detection technology, and particularly to a visible light detector and a preparation method thereof. Background Art

[0002] With the development of the new generation of wireless communication technology, the huge spectral resources in the visible light band make visible light communication technology play a crucial role in the new generation of mobile communication technology. As a semiconductor device that can convert the detected optical signal into an electrical signal, a visible light detector is one of the key devices that determine the quality of the entire visible light communication system. In

[0010] ,

[0009] ,

[0008] , , Ga 1-x N(0 < x < 1) has an adjustable bandgap ranging from 0.68 eV to 3.4 eV, which enables it to achieve light detection for the entire visible light spectrum. Moreover, InGaN materials have advantages such as good wavelength selectivity, high saturated electron mobility, direct bandgap, and high band-edge optical absorption coefficient. Therefore, InGaN-based visible light detectors are more conducive to meeting the requirements of high-speed visible light communication systems.

[0003] One-dimensional InGaN nanorods / nanopillars / nanowire materials can significantly increase light absorption and photo-generated carrier density due to their large surface-to-volume ratio; moreover, the short and direct transport path of the one-dimensional nanostructure can also effectively shorten the carrier transport time, facilitating fast optical response. Currently, however, InGaN nanorods face the problem that a large number of surface states affect the transport of photo-generated carriers, and at the same time, the surface states capture photo-generated carriers, reducing the optical response current of the device. This makes it necessary to further optimize the design for the realization of high-performance InGaN nanorod visible light detectors. In this regard, we use PEDOT:PSS to passivate the surface states and introduce Au nanoparticles at the same time to improve the incident light field and enhance light absorption. Summary of the Invention

[0004] The purpose of the present invention is to overcome the above-mentioned drawbacks and deficiencies of the prior art, and to provide a visible light detector and a preparation method thereof.

[0005] The present invention is realized through the following technical solutions:

[0006] A visible light detector, the structure of the visible light detector includes:

[0007] A single-crystalline silicon substrate;

[0008] InGaN nanorods and a first metal electrode located on the upper surface of the single-crystalline silicon substrate;

[0009] A mixed solution of gold nanoparticles and PEDOT:PSS located on the surface of the InGaN nanorods;

[0010] A second metal electrode is located on the InGaN nanorod coated with a mixture of gold nanoparticles and PEDOT:PSS solution.

[0011] The first metal electrode is a Ti / Au alloy electrode, with a Ti thickness of 20–30 nm and an Au thickness of 250–350 nm.

[0012] The second metal electrode is an Ag electrode with a thickness of 200–300 nm.

[0013] The InGaN nanorods have an In content of 0.1–0.2%, a height of 200–500 nm, and a diameter of 30–80 nm.

[0014] The gold nanoparticles have a diameter of 10-30 nm and a concentration of 0.05-0.2 mg / mL.

[0015] PEDOT:PSS concentration is 1% to 3% wt%.

[0016] The volume ratio of gold nanoparticles to PEDOT:PSS mixed solution is 2:1 to 1:2.

[0017] The present invention provides a method for fabricating a visible light detector, comprising the following steps:

[0018] S1. Clean the single-crystal silicon substrate and grow InGaN nanorods on the single-crystal silicon substrate using an MBE device;

[0019] S2, Mask deposition of the first metal electrode;

[0020] S3. Mix the solution of gold nanoparticles and PEDOT:PSS at a certain solution volume ratio and stir magnetically at 1500 rpm for 1 hour.

[0021] S4. Protect the electrode deposited in S2 to prevent the mixed solution from being spin-coated onto the first metal electrode. Then spin-coat the mixed solution onto the grown InGaN nanorods at a spin coater speed of 2000 rpm for 15 s. After spin-coating the mixed solution, anneal the sample at 100 °C for 10 min.

[0022] S5. A second metal electrode is deposited on an InGaN nanorod spin-coated with a mixed solution.

[0023] Compared with the prior art, the present invention has the following advantages and effects:

[0024] This invention relates to an InGaN nanorod structure coated with gold nanoparticles and a PEDOT:PSS mixed solution. The use of PEDOT:PSS effectively passivates the surface states of the InGaN nanorods, suppressing the trapping of photogenerated carriers by these surface states while simultaneously improving the transport of photogenerated carriers.

[0025] This invention utilizes gold nanoparticles to induce surface plasmon resonance, thereby improving light absorption and increasing photoresponse current. The introduction of PEDOT:PSS effectively passivates the surface states of InGaN nanorods, reducing dark current; the introduction of gold nanoparticles induces surface plasmon resonance, enhancing photoresponse current. Compared to detectors without gold nanoparticle and PEDOT:PSS mixed solution modification, this detector exhibits higher photocurrent and lower dark current.

[0026] This invention has the advantages of low cost, excellent performance and simple preparation.

[0027] The visible light detector and its fabrication method provided by this invention can be applied to the field of visible light communication. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the visible light detector of the present invention;

[0029] Figure 2 This is a flowchart illustrating the fabrication process of the visible light detector of the present invention.

[0030] Figure 3 These are cross-sectional views and top views of the InGaN nanorods of the present invention.

[0031] Figure 4 The images show the visible light detector of the present invention under both light and dark conditions, as well as the visible light characteristic curves of the gold-free nanoparticle and PEDOT:PSS-coated InGaN nanorod devices.

[0032] Figure 5 The transient response curve of the visible light detector of the present invention is shown below.

[0033] in, Figure 1 In the diagram: 101 is a single-crystal silicon substrate, 102 is the first metal electrode, 103 is PEDOT:PSS, 104 is gold nanoparticles, 105 is InGaN nanorods, and 106 is the second metal electrode. Detailed Implementation

[0034] The present invention will now be described in further detail with reference to specific embodiments.

[0035] like Figure 1 As shown, this invention discloses a visible light detector.

[0036] The visible light detector structure includes:

[0037] A single-crystal silicon substrate 101, an InGaN nanorod 105 and a first metal electrode 102 located on the upper surface of the single-crystal silicon substrate 101; a mixed solution of gold nanoparticles 104 and PEDOT:PSS 103 located on the surface of the InGaN nanorod 105; and a second metal electrode 106 located on the InGaN nanorod 105 coated with the mixed solution of gold nanoparticles 104 and PEDOT:PSS 103.

[0038] The method for fabricating the visible light detector, such as... Figure 2 As shown, the specific steps include:

[0039] S1. The single-crystal silicon substrate was ultrasonically cleaned for 10 minutes in sequence with acetone, isopropanol and deionized water. InGaN nanorods were grown on the 2-inch single-crystal silicon substrate using an MBE epitaxial device. The substrate temperature was 900℃, the substrate rotation speed was 5r / min, the plasma power was 300W and the growth time was 2h.

[0040] S2. Protect the InGaN nanorod region from metal deposition using a hard mask, and deposit Ti / Au alloy as the first metal electrode using an electron beam evaporation device. The thickness of Ti is 20 nm and the thickness of Au is 300 nm.

[0041] S3. Transfer a 0.05 mg / mL gold nanoparticle colloidal solution (5 mL) using a pipette, and transfer a 1.3 wt% PEDOT:PSS solution (10 mL) using a pipette. Mix the two solutions and stir magnetically at 1500 rpm for 1 h.

[0042] S4. Protect the electrode deposited in S2 to prevent the mixed solution from being spin-coated onto the first metal electrode. Then spin-coat the mixed solution onto the grown InGaN nanorods at a spin coater speed of 2000 rpm for 15 s. After spin-coating the mixed solution, anneal the sample at 100 °C for 10 min.

[0043] S5. Expose the InGaN nanorod region through a hard mask, and deposit Ag as a second metal electrode on the InGaN nanorods that have been spin-coated with a mixed solution. The thickness of the Ag metal film is 300 nm.

[0044] Material characterization and performance testing:

[0045] The visible light detector prepared according to the embodiments of the present invention was characterized as follows:

[0046] like Figure 3As shown, the left side is a cross-sectional SEM image of InGaN nanorods grown on a silicon substrate, and the right side is a top view. It can be seen that the nanorods are clustered together relatively tightly. The diameter of the nanorods is about 50 nm and the length of the nanorods is about 270 nm.

[0047] The photoelectric performance of the visible light detector prepared according to the embodiments of the present invention was tested:

[0048] To demonstrate the gain effect of this patent, a set of comparative experiments were conducted in this embodiment, namely, an InGaN / Si visible light detector with InGaN nanorods coated with a mixture of gold nanoparticles and PEDOT:PSS. For example... Figure 4 The IV characteristic curves shown indicate that, under 420nm visible light illumination and a -2V reverse bias, the visible light detector of this invention exhibits higher photoresponse current and lower dark current.

[0049] like Figure 5 As shown, transient optical response characteristic analysis indicates that the rise / fall time is 6.2 s.

[0050] As described above, the present invention can be implemented well.

[0051] The implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A visible light detector, characterized in that, The visible light detector structure includes: Single-crystal silicon substrate; InGaN nanorods and a first metal electrode located on the upper surface of the single-crystal silicon substrate; Gold nanoparticles located on the surface of the InGaN nanorods and a PEDOT:PSS mixed solution; A second metal electrode is located on an InGaN nanorod coated with a mixture of gold nanoparticles and PEDOT:PSS solution.

2. The visible light detector according to claim 1, characterized in that, The first metal electrode is a Ti / Au alloy electrode, with a Ti thickness of 20-30 nm and an Au thickness of 250-350 nm.

3. The visible light detector according to claim 1, characterized in that, The second metal electrode is an Ag electrode with an Ag thickness of 200–300 nm.

4. The visible light detector according to claim 1, characterized in that, The InGaN nanorods have an In content of 0.1–0.2%, a height of 200–500 nm, and a diameter of 30–80 nm.

5. The visible light detector according to claim 1, characterized in that, The gold nanoparticles have a diameter of 10-30 nm and a concentration of 0.05-0.2 mg / mL.

6. The visible light detector according to claim 1, characterized in that, The concentration of PEDOT:PSS is 1% to 3% wt%.

7. The visible light detector according to claim 1, characterized in that, The volume ratio of the gold nanoparticles to the PEDOT:PSS mixed solution is 2:1 to 1:

2.

8. The method for fabricating a visible light detector according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Clean the single-crystal silicon substrate and grow InGaN nanorods on the single-crystal silicon substrate using an MBE device; S2, Mask deposition of the first metal electrode; S3, a solution of mixed gold nanoparticles and PEDOT:PSS, was stirred magnetically at 1500 rpm for 1 h; S4. Protect the electrode deposited in step S2 to prevent the mixed solution from being spin-coated onto the first metal electrode. Then spin-coat the mixed solution onto the grown InGaN nanorods at a spin coater speed of 2000 rpm for 15 s. Anneal the sample after spin-coating the mixed solution at 100 °C for 10 min. S5. A second metal electrode is deposited on an InGaN nanorod spin-coated with a mixed solution.

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