钙钛矿材料窄带光电探测器中组分调控策略及性能提升研究进展

金属卤化物钙钛矿因具有宽范围可调带隙、高光吸收系数、长载流子扩散长度和低温柔性兼容等优点,被视为构建窄带探测器的理想光吸收材料,在仿生人眼、颜色分辨和彩色成像等领域中有着潜在应用。然而,目前窄带探测器响应度和外量子效率仍然较低,严重阻碍了其进一步发展。钙钛矿窄带探测器的响应主要依赖于光吸收层带隙,而带隙取决于制备工艺和化学组分。尽管关于钙钛矿薄膜制备已有较多报道,但基于组分调控的窄带响应探测方面的总结较少,因此提高窄带钙钛矿探测器响应度和外量子效率等问题亟待解决。总结了近年来不同体系钙钛矿材料在组分调控方面的研究进展,其中包括有机无机铅卤钙钛矿和全无机铅卤钙钛矿,着重对比了不同材料体系中的组分调控策略,归纳了窄带响应的物理机理,旨在梳理通过组分调控提升钙钛矿窄带探测器性能及特定波段光响应方面的研究进展,为窄带钙钛矿探测器进一步应用提供研究基础和理论指导。     

n-ZnO/p-Si紫外至近红外增强型广谱光探测器

采用直流反应溅射法,在一定的溅射功率和衬底温度等条件下控制气体组分,优选Ar:O2＝8:1成功研制出高响应度n-ZnO/p-Si紫外至近红外增强型广谱光探测器.实验关键是利用缺O法在n-ZnO薄膜内有效引入O缺位Vo,而Vo可增强紫蓝波段的光响应.测试结果显示,ZnO薄膜的光致发光(PL)谱除在388 nm处存在紫外带边发射主峰外,还在416 nm处出现由O缺位导致的发射峰;X射线衍射(XRD)谱表明,薄膜中的晶体为高c轴取向的纤锌矿结构;n-ZnO/p-Si光探测器在光照时I-V特性显示,光电流随反向偏压的增加迅速上升;在5 V的反向偏压下,紫外区(310～388 nm)的光响应高达0.75～1.38 A/W,紫蓝光区(400～430 nm)的光响应大大增强,400～800 nm波段的光谱响应稳定在0.90 A/W.     

表面敏化改性纳米晶TiO2的光谱响应特性研究及其应用进展

介绍了各类敏化剂对纳米晶TiO2的敏化作用机制,并从能带匹配角度分析了敏化剂选择的原则,综述了近期国内外敏化改性纳米晶TiO2在拓宽光谱响应范围、提高TiO2光谱响应性能的研究成果,简要概述了敏化TiO2在太阳能电池、环境净化、光解水制备氢等方面的应用,最后对敏化法改性TiO2的研究方向与材料应用前景进行了探讨.     

Enhanced UV photosensitivity from rapid thermal annealed vertically aligned ZnO nanowires

We report on the major improvement in UV photosensitivity and faster photoresponse from vertically aligned ZnO nanowires (NWs) by means of rapid thermal annealing (RTA). The ZnO NWs were grown by vapor-liquid-solid method and subsequently RTA treated at 700°C and 800°C for 120 s. The UV photosensitivity (photo-to-dark current ratio) is 4.5 × 10³ for the as-grown NWs and after RTA treatment it is enhanced by a factor of five. The photocurrent (PC) spectra of the as-grown and RTA-treated NWs show a strong peak in the UV region and two other relatively weak peaks in the visible region. The photoresponse measurement shows a bi-exponential growth and bi-exponential decay of the PC from as-grown as well as RTA-treated ZnO NWs. The growth and decay time constants are reduced after the RTA treatment indicating a faster photoresponse. The dark current-voltage characteristics clearly show the presence of surface defects-related trap centers on the as-grown ZnO NWs and after RTA treatment it is significantly reduced. The RTA processing diminishes the surface defect-related trap centers and modifies the surface of the ZnO NWs, resulting in enhanced PC and faster photoresponse. These results demonstrated the effectiveness of RTA processing for achieving improved photosensitivity of ZnO NWs.     

一种制备Au/n-Al0.3Ga0.7N横向肖特基二极管的方法

用MOCVD生长未掺杂n-Al0.3Ga0.7N制备了MSM结构紫外探测器,并通过电击穿MSM右边肖特基势垒而制成了横向肖特基二极管.器件在零偏电压处的背景光电流为87.3 pA.从器件的室温I-V特性曲线计算出理想因子n、零偏势垒高度B0和串联电阻RS分别为1.99、0.788 eV和10.2 kΩ.器件在305 nm波长处有陡峭的截止边,300 nm峰值波长处电流响应率为0.034 A/W.     

超导Y－Ba－Cu－O薄膜对632．8nm激光的响应

本文报导超导Ｙ—Ｂａ－Ｃｕ—Ｏ薄膜在临界温度附近对６３２．８ｎｍ激光的响应。实验结果表明，光响应包含可用测辐射热计效应解释的热成分和不能用热效应解释的非热的光成分。并介绍一种新的、加偏置连续激光的检测光响应的实验方法，发现在较高的调制频率时偏置激光能提高超导薄膜样品对可见光的探测灵敏度。     

Anomalous and Polarization‐Sensitive Photoresponse of Td‐WTe2 from Visible to Infrared Light

Recently, an emergent layered material T_d‐WTe₂ was explored for its novel electron–hole overlapping band structure and anisotropic inplane crystal structure. Here, the photoresponse of mechanically exfoliated WTe₂ flakes is investigated. A large anomalous current decrease for visible (514.5 nm), and mid‐ and far‐infrared (3.8 and 10.6 µm) laser irradiation is observed, which can be attributed to light‐induced surface bandgap opening from the first‐principles calculations. The photocurrent and responsivity can be as large as 40 µA and 250 A W^?1 for a 3.8 µm laser at 77 K. Furthermore, the WTe₂ anomalous photocurrent matches its in‐plane crystal structure and exhibits light polarization dependence, maximal for linear laser polarization along the W atom chain a direction and minimal for the perpendicular b direction, with the anisotropic ratio of 4.9. Consistently, first‐principles calculations confirm the angle‐dependent bandgap opening of WTe₂ under polarized light irradiation. The anomalous and polarization‐sensitive photoresponses suggest that linearly polarized light can significantly tune the WTe₂ surface electronic structure, providing a potential approach to detect polarized and broadband lights up to far infrared range.     

A Novel Way to Fabricate Fe Doped TiO2 Nanotubes by Anodization of TiFe Alloys

研究在乙二醇和NH4F混合电解液中通过阳极氧化Ti-xFe合金制备自组装、高度有序的Ti-Fe-O纳米管阵列薄膜,以及该薄膜的Uv-Vis(200-1000nm)光响应性能。薄膜形貌的关键影响因素为Fe含量。随着Fe含量的增加,纳米管阵列的表面越平整,而纳米管的底部越无序。GAXRD和光响应测试表明,Fe成功地掺杂在纳米管层中,并导致纳米管具有明显的可见光响应。利用该工艺在Ti-12Fe合金表面制备的样品在可见光谱范围内具有大的光响应能力。