论文标题
带有表面氧化物控制的高光学增益
Broad Band Single Germanium Nanowire Photodetectors with Surface Oxide Controlled High Optical Gain
论文作者
论文摘要
我们已经研究了在300至1100 nm的光谱范围内的单晶型纳米线（NWS）的光电传射性能，显示超过10^{7} aw^{ - 1}的超大峰值响应性。在本报告中，我们讨论了超大响应能力的可能起源，可能是由各种物理效应的组合a）：ge和geo_和geo_ {x}界面状态，这些状态充当照相生成对的电子清除剂，使孔自由到达电气范围内的电气和nw接触量较低的电气范围的孔中，这些孔可在金属和nw界面上差异，该镜头的范围差异很小，该镜头的范围差异很大。小（大约很少μm），由于缺陷部位的重组而导致的光生载体可忽略不计。我们已经从光学增益的功率依赖性观察到，增益受陷阱状态控制。我们发现纳米线的表面具有提供界面状态的薄薄的geo_ {x}（从HRTEM研究中证明的）。据观察，这些状态起着至关重要的作用，可以为分离光生的电子和孔对分离径向场，进而导致非常高的有效光导数增益，在低照明密度下达到很高的光电传统增益。
We have investigated photoconductive properties of single Germanium Nanowires(NWs)of diameter less than 100 nm in the spectral range of 300 to 1100 nm showing ultra large peak Responsivity in excess of 10^{7}AW^{-1}.The NWs were grown by Vapor Liquid Solid method using Au nanoparticle as catalyst. In this report we discuss the likely origin of the ultra large responsivity that may arise from a combination of various physical effects which are a): Ge and GeO_{x} interface states which act as scavengers of electrons from the photo-generated pairs,leaving the holes free to reach the electrodes,b) Schottky barrier at the metal and NW interface which gets lowered substantially due to carrier diffusion in contact region and (c) photodetector length being small (approximately few μm), negligible loss of photogenerated carriers due to recombination at defect sites. We have observed from power dependence of the optical gain that the gain is controlled by trap states. We find that the surface of the nanowire has presence of a thin layer of GeO_{x} (as evidenced from HRTEM study) which provide interface states. It is observed that these state play a crucial role to provide a radial field for separation of photogenerated electron and hole pair which in turn leads to very high effective photoconductive gain that reaches a very high at low illumination density.
