基于AZO籽晶层生长ZnO纳米棒阵列异质结光电响应特性的研究

发布时间：2018-06-25 20:24

本文选题：AZO籽晶层薄膜 + ZnO　；参考：《天津理工大学》2017年硕士论文

【摘要】：ZnO是典型的n型宽禁带半导体,具有优异的光学和电学性质。一维ZnO纳米棒阵列(ZnO NRs)具有比表面积大,电子定向传输等优势,被广泛应用于紫外光探测器。但是ZnO NRs表面和体内缺陷较多,作为载流子捕获中心,不利于载流子传输。基于ZnO NRs异质结的紫外光探测器性能如光灵敏度、光响应速度、光响应率等有待进一步提高。有效降低ZnO NRs缺陷态和表面态,提高载流子传输是ZnO NRs基光探测器亟待解决的问题。本论文利用简单的化学浴沉积法制备ZnO NRs,利用Al掺杂ZnO籽晶层薄膜(AZO)调控ZnO NRs形貌、结晶质量以及光电性能。将ZnO NRs分别与Au电极构筑肖特基结,与CuSCN和MoS_2纳米片复合构筑异质结,利用结区内建电场促使光生载流子有效分离。具体研究内容和结果如下:(1)在不同Al掺杂浓度的AZO籽晶层薄膜上生长ZnO NRs,研究AZO籽晶层薄膜对ZnO NRs形貌、结晶质量以及光电性能的影响,进而研究Au/ZnO NRs/AZO肖特基结光电响应特性。研究表明Al掺杂浓度为0.5%的AZO籽晶层(AZO(0.5%))薄膜表面粗糙度小,透光率高且载流子浓度大。AZO(0.5%)籽晶层薄膜生长的ZnO NRs比较致密、结晶质量较好、缺陷较少、紫外透光性高、载流子浓度大、表面耗尽区窄。致密的ZnO NRs与Au电极紧密的接触降低了漏电流。Au/ZnO NRs/AZO肖特基结在+2 V偏压,360 nm(3.2 mW/cm2)紫外光照下呈现光电响应特性,并且AZO(0.5%)籽晶层薄膜生长ZnO NRs构筑的肖特基结光电流和光响应率较大。(2)在AZO籽晶层薄膜生长的ZnO NRs上电化学沉积CuSCN,构筑p-CuSCN/n-ZnO NRs异质结,研究异质结的紫外光电响应特性。研究发现电化学沉积的CuSCN颗粒呈类金字塔形,且完全覆盖了ZnO NRs表面。CuSCN薄膜避免了Au电极和ZnO NRs直接接触,减小了异质结的漏电流。电学测试结果表明CuSCN/ZnO NRs异质结具有整流特性,光照下有光伏效应,在无外加电场的驱动下可以实现自驱动光响应。无外加电场驱动下,CuSCN/ZnO NRs异质结对紫外光具有很好的光谱选择性,并且AZO(0.5%)籽晶层薄膜生长ZnO NRs构筑的CuSCN/ZnO NRs异质结自驱动光电流较大,响应率约为22.5 m A/W,这可归因于增强的ZnO NRs紫外光吸收和良好的载流子传输特性。(3)在AZO(0.5%)籽晶层薄膜生长的ZnO NRs上旋涂液相剥离获得的MoS_2纳米片,构筑MoS_2/ZnO NRs异质结,研究其光电响应特性。研究发现MoS_2纳米片垂直站立于ZnO NRs表面,异质结呈现紫外光、红光波段光电响应特性。MoS_2纳米片层数越少,电子沿层内传输的通道越多,MoS_2纳米片与ZnO NRs表面的接触电阻越小,异质结在紫外区和红光区呈现出的光电流、光响应率越大。
[Abstract]:ZnO is a typical n-type wide band gap semiconductor with excellent optical and electrical properties. One-dimensional ZnO nanorod arrays (ZnO NRs) are widely used in UV detectors for their advantages of large specific surface area and directional electron transport. However, there are many defects in the surface and body of ZnO NRs, which are not conducive to carrier transport as carrier trapping centers. The performance of UV photodetectors based on ZnO NRS heterojunction, such as photosensitivity, photoresponse speed and photoresponsivity, need to be further improved. It is an urgent problem for ZnO NRs based photodetectors to reduce the defect states and surface states of ZnO NRs effectively and improve the carrier transport. In this paper, ZnO NRswere prepared by simple chemical bath deposition. The morphology, crystallization quality and optoelectronic properties of ZnO NRs were regulated by Al doped ZnO seed layer thin films (AZO). Schottky junctions of ZnO NRs with au electrodes and heterojunction with CuSCN and MoS2 nanochips were constructed respectively. The photocarriers were effectively separated by electric field in the junction region. The main contents and results are as follows: (1) ZnO NRs were grown on different Al doped AZO seed films. The effects of AZO seed films on the morphology, crystallization quality and photoelectric properties of ZnO NRs were investigated, and the photoelectric response characteristics of Au/ ZnO NRsr / AZO Schottky junctions were studied. The results show that the AZO seed layer (AZO (0.5%) with 0.5% Al doping has a low surface roughness, a high transmittance and a high carrier concentration. The ZnO NRs grown by the seed layer of 0.5% AZO (0.5%) are compact, the quality of crystallization is better, the defect is less, and the UV transmittance is high. The carrier concentration is high and the surface depletion area is narrow. The close contact between the dense ZnO NRs and the au electrode reduces the leakage current. Aur / ZnO NRs / AZO Schottky junctions exhibit photoelectric response under 2 V bias at 360 nm (3.2 MW / cm 2) UV light. Moreover, the Schottky junction constructed by ZnO NRs grown by AZO (0.5%) seed layer film has a high photocurrent and photoresponse. (2) CuSCN was deposited on ZnO NRs grown in AZO seed layer film, and p-CuSCN / n-ZnO NRs heterojunction was constructed, and the UV photoelectric response of the heterojunction was studied. It was found that the CuSCN particles deposited by electrochemical deposition were pyramidal and completely covered with the surface of ZnO NRs. The direct contact between au electrode and ZnO NRs was avoided, and the leakage current of heterojunction was reduced. The results of electrical measurement show that CuSCN / ZnO NRs heterojunction has the characteristics of rectifying, photovoltaic effect under illumination, and the self-driving light response can be realized without external electric field. The heterojunction of CuSCN / ZnO NRs without external electric field has a good spectral selectivity to ultraviolet light, and the CuSCN / ZnO NRs heterojunction grown by AZO (0.5%) seed layer films has a large self-driving photocurrent. The responsivity is about 22.5 Ma / W, which can be attributed to the enhanced UV light absorption of ZnO NRs and good carrier transport properties. (3) MoS2 nanocrystals grown on the surface of AZO (0.5%) seed layer ZnO NRs are fabricated by spin-coated liquid stripping, and MoS2 / ZnO NRs heterostructures are constructed. The photoelectric response characteristics are studied. It is found that the surface of ZnO NRs is perpendicular to the surface of MOS2 nanoplates. The heterojunction exhibits ultraviolet light. The smaller the number of layers, the smaller the contact resistance of MoS2 nanoparticles and ZnO NRs is. The photocurrent of the heterojunction in the ultraviolet and red region increases the photoresponse rate.
【学位授予单位】：天津理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN304.21

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