Solid State Physics and NanoLund, Lund University , Box 118, SE-221 00 Lund, Sweden.
Department of Mathematics, Physics and Electrical Engineering, Halmstad University , Box 823, SE-301 18 Halmstad, Sweden.
Nano Lett. 2017 Jun 14;17(6):3356-3362. doi: 10.1021/acs.nanolett.6b05114. Epub 2017 May 31.
The possibility to engineer nanowire heterostructures with large bandgap variations is particularly interesting for technologically important broadband photodetector applications. Here we report on a combined study of design, fabrication, and optoelectronic properties of infrared photodetectors comprising four million n-i-n InP nanowires periodically ordered in arrays. The nanowires were grown by metal-organic vapor phase epitaxy on InP substrates, with either a single or 20 InAsP quantum discs embedded in the i-segment. By Zn compensation of the residual n-dopants in the i-segment, the room-temperature dark current is strongly suppressed to a level of pA/NW at 1 V bias. The low dark current is manifested in the spectrally resolved photocurrent measurements, which reveal strong photocurrent contributions from the InAsP quantum discs at room temperature with a threshold wavelength of about 2.0 μm and a bias-tunable responsivity reaching 7 A/W@1.38 μm at 2 V bias. Two different processing schemes were implemented to study the effects of radial self-gating in the nanowires induced by the nanowire/SiO/ITO wrap-gate geometry. Summarized, our results show that properly designed axial InP/InAsP nanowire heterostructures are promising candidates for broadband photodetectors.
具有大带隙变化的纳米线异质结构的工程化对于技术上重要的宽带光电探测器应用特别有趣。在这里，我们报告了一项关于设计、制造和光电特性的综合研究，该研究涉及由四百万个 n-i-n InP 纳米线组成的周期性排列的阵列组成的红外光电探测器。纳米线通过金属有机气相外延在 InP 衬底上生长，i 段中嵌入有单个或 20 个 InAsP 量子盘。通过对 i 段中残余 n 型掺杂剂的 Zn 补偿，室温暗电流被强烈抑制到 1 V 偏压下 pA/NW 的水平。低暗电流在光谱分辨光电流测量中表现出来，该测量揭示了室温下 InAsP 量子盘的强光电流贡献，其阈值波长约为 2.0 μm，在 2 V 偏压下可调响应率达到 7 A/W@1.38 μm。实施了两种不同的处理方案来研究由纳米线/SiO/ITO 环绕栅极几何形状引起的纳米线径向自栅效应的影响。总之，我们的结果表明，适当设计的轴向 InP/InAsP 纳米线异质结构是宽带光电探测器的有前途的候选者。
