论文标题
通过径向场有效分离光生的电子孔对，促进了单个半导体纳米型光电探测器的超高光响应
Effective separation of photogenerated electron-hole pairs by radial field facilitates ultrahigh photoresponse in single semiconductor nanowire photodetectors
论文作者
论文摘要
我们报告了对直径<100 nm的单纳米线光探测器中超高光响应（Photogain，g_pc> 106）观察的研究。这项研究是实验观测和对半导体纳米线的超高光学响应的理论分析的结合，重点是GE纳米线。半导体纳米线光电探测器显示出光吸收的标志，其中g_pc随着照明强度的增加而滚动。我们表明，由于纳米线中耗尽的表面层而引起的表面带弯曲会诱导强烈的径向场（在纳米线表面〜108 v/m），从而导致光生的电子孔对物理分离。这是通过基于耦合Schrodinger和Poisson方程的自洽理论模型进行定量建立的。它表明，载体分离将表面重组速度降低到低值（<1 cm/s），从而将载体重组率降低，并将重组寿命延长几个数量级。该模型的重要结果是单个GE纳米线（直径60 nm）中G_PC〜106的预测与我们的实验观察非常匹配。该模型还显示了G_PC对直径的逆依赖性，该直径已通过实验观察到。尽管在GE纳米线的背景下进行了，但开发的物理模型也在其他半导体纳米线中也具有一般适用性。
We report an investigation on the observation of ultrahigh photoresponse (photogain, G_Pc>106) in single nanowire photodetectors of diameter < 100 nm. The investigation which is a combination of experimental observations and a theoretical analysis of the ultrahigh optical response of semiconductor nanowires, has been carried out with emphasis on Ge nanowires. Semiconductor nanowire photodetectors show a signature of photogating where G_Pc rolls-off with increasing illumination intensity. We show that surface band bending due to depleted surface layers in nanowires induces a strong radial field (~ 108 V/m at the nanowire surface) which causes physical separation of photogenerated electron-hole pairs. This was established quantitatively through a self-consistent theoretical model based on coupled Schrodinger and Poisson Equations. It shows that carrier separation slows down the surface recombination velocity to a low value (< 1 cm/s) thus reducing the carrier recombination rate and extending the recombination lifetime by few orders of magnitude. An important outcome of the model is the prediction of G_Pc ~ 106 in a single Ge nanowire (with diameter 60 nm), which matches well with our experimental observation. The model also shows an inverse dependence of G_Pc on the diameter that has been observed experimentally. Though carried out in context of Ge nanowires, the physical model developed has general applicability in other semiconductor nanowires as well.
