Direct observation of shift and ballistic photovoltaic currents
Direct observation of shift and ballistic photovoltaic currents
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DOI：
10.1126/sciadv.aau5588
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发表时间：
2019-01-01
期刊：
影响因子：
13.6
通讯作者：
Spanier, Jonathan E.
中科院分区：
文献类型：
--
作者：
Burger, Aaron M.;Agarwal, Radhe;Spanier, Jonathan E.
移位光伏电流的量子现象早在几十年前就被预测到了，但由于移位电流和弹道电流并存，这种效应从未被直接观察到。原子尺度的位移弛豫时间，加上没有光学霍尔行为，使得对位移的决定性测量变得难以捉摸。在这里，我们报告了一种简便的、直流的稳态方法，通过同时测量磁场下的线性和圆形光伏电流，可以明确地确定硅酸盐压电晶体中的位移。通过与理论预测的比较，可以估计出移位的签名长度尺度。值得注意的是，在单色照明下，移位和弹道光伏电流同时向相反的方向流动。将漂移和弹道贡献分开，为定量、基本地洞察和实际理解这些截然不同的光伏电流机制及其关系开辟了道路。
The quantum phenomenon of shift photovoltaic current was predicted decades ago, but this effect was never observed directly because shift and ballistic currents coexist. The atomic-scale relaxation time of shift, along with the absence of a photo-Hall behavior, has made decisive measurement of shift elusive. Here, we report a facile, direct-current, steady-state method for unambiguous determination of shift by means of the simultaneous measurements of linear and circular bulk photovoltaic currents under magnetic field, in a sillenite piezoelectric crystal. Comparison with theoretical predictions permits estimation of the signature length scale for shift. Remarkably, shift and ballistic photovoltaic currents under monochromatic illumination simultaneously flow in opposite directions. Disentangling the shift and ballistic contributions opens the way for quantitative, fundamental insight into and practical understanding of these radically different photovoltaic current mechanisms and their relationship.