Yu Jinling, Xia Lijia, Zhu Kejing, Pan Qinggao, Zeng Xiaolin, Chen Yonghai, Liu Yu, Yin Chunming, Cheng Shuying, Lai Yunfeng, He Ke, Xue Qikun
Institute of Micro/Nano Devices and Solar Cells, School of Physics and Information Engineering, Fuzhou University, Fuzhou 350108, China.
Department of Physics, State Key Laboratory of Low Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China.
ACS Appl Mater Interfaces. 2020 Apr 15;12(15):18091-18100. doi: 10.1021/acsami.9b23389. Epub 2020 Apr 6.
The circular photogalvanic effect (CPGE) provides a method utilizing circularly polarized light to control spin photocurrent and will also lead to novel opto-spintronic devices. The CPGE of three-dimensional topological insulator BiTe with different substrates and thicknesses has been systematically investigated. It is found that the CPGE current can be dramatically tuned by adopting different substrates. The CPGE current of the BiTe films on Si substrates are more than two orders larger than that on SrTiO substrates when illuminated by 1064 nm light, which can be attributed to the modulation effect due to the spin injection from Si substrate to BiTe films, larger light absorption coefficient, and stronger inequivalence between the top and bottom surface states for BiTe films grown on Si substrates. The excitation power dependence of the CPGE current of BiTe films on Si substrates shows a saturation at high power especially for thicker samples, whereas that on SrTiO substrates almost linearly increases with excitation power. Temperature dependence of the CPGE current of BiTe films on Si substrates first increases and then decreases with decreasing temperature, whereas that on SrTiO substrates changes monotonously with temperature. These interesting phenomena of the CPGE current of BiTe films on Si substrates are related to the spin injection from Si substrates to BiTe films. Our work not only intrigues new physics but also provides a method to effectively manipulate the helicity-dependent photocurrent via spin injection.
圆光电电流效应（CPGE）提供了一种利用圆偏振光来控制自旋光电流的方法，并且还将催生新型光自旋电子器件。已对具有不同衬底和厚度的三维拓扑绝缘体BiTe的CPGE进行了系统研究。研究发现，通过采用不同的衬底可以显著调节CPGE电流。当用1064 nm光照射时，Si衬底上BiTe薄膜的CPGE电流比SrTiO衬底上的大两个数量级以上，这可归因于从Si衬底到BiTe薄膜的自旋注入、更大的光吸收系数以及在Si衬底上生长的BiTe薄膜的上下表面态之间更强的不等价性所产生的调制效应。Si衬底上BiTe薄膜的CPGE电流对激发功率的依赖性在高功率下呈现饱和，特别是对于较厚的样品，而在SrTiO衬底上则几乎随激发功率线性增加。Si衬底上BiTe薄膜的CPGE电流的温度依赖性随温度降低先增加后减小，而在SrTiO衬底上则随温度单调变化。Si衬底上BiTe薄膜的CPGE电流的这些有趣现象与从Si衬底到BiTe薄膜的自旋注入有关。我们的工作不仅引发了新的物理学研究，还提供了一种通过自旋注入有效操纵与螺旋度相关的光电流的方法。
