Band alignment of type-Ⅰ SnS_(2)/Bi_(2)Se_(3) and type-Ⅱ SnS_(2)/Bi_(2)Te_(3) van der Waals heterostructures for highly enhanced photoelectric responses  

构建Ⅰ型SnS_(2)/Bi_(2)Se_(3)和Ⅱ型SnS_(2)/Bi_(2)Te_(3)范德瓦尔斯异质结构提升其光电性能

作　　者：Mingwei Luo Chunhui Lu Yuqi Liu Taotao Han Yanqing Ge Yixuan Zhou Xinlong Xu 罗铭威;卢春辉;刘玉琪;韩涛涛;葛燕青;周译玄;徐新龙(Shaanxi Joint Lab of Graphene,State Key Laboratory of Photon-Technology in Western China Energy,International Collaborative Center on Photoelectric Technology and Nano Functional Materials,Institute of Photonics&Photon-Technology,School of Physics,Northwest University,Xi’an,710069,China)

机构地区：[1]Shaanxi Joint Lab of Graphene,State Key Laboratory of Photon-Technology in Western China Energy,International Collaborative Center on Photoelectric Technology and Nano Functional Materials,Institute of Photonics&Photon-Technology,School of Physics,Northwest University,Xi’an,710069,China

出　　处：《Science China Materials》2022年第4期1000-1011,共12页中国科学（材料科学（英文版）

基　　金：supported by the National Natural Science Foundation of China(12074311,11774288,11974279);the Natural Science Foundation of Shaanxi Province(2019JC-25)。

摘　　要：Heterostructures based on new advanced materials offer a cornerstone for future optoelectronic devices with improved photoelectric performance.Band alignment is crucial for understanding the mechanism of charge carrier transportation and interface dynamics in heterostructures.Herein,we grew SnS_(2)/Bi_(2)X_(3)(X=Se,Te)van der Waals heterostructures by combining physical vapor deposition with chemical vapor deposition.The band alignment,measured by high-resolution X-ray photoelectron spectroscopy,suggested the successful design of type-Ⅰ SnS_(2)/Bi_(2)Te_(3) and type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructures.The SnS_(2)/Bi_(2)X_(3) heterostructure greatly improved the photoelectric response of a photoelectrochemical-type photodetector.The photocurrent densities in the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) and type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructure-based devices were more than one order of magnitude higher than those of SnS_(2),Bi_(2)Te_(3),and Bi_(2)Te_(3).The improved photoelectric properties of the SnS_(2)/Bi_(2)X_(3) heterostructures can be explained as follows:(i)the photoexcited electrons and holes are effectively separated in the heterostructures;(ii)the charge-transfer efficiency and carrier density at the interface between the SnS_(2)/Bi_(2)X_(3) heterostructures and the electrolyte are greatly improved;(iii)the formed heterostructures expand the light absorption range.The photoelectric performance was further enhanced by efficient light trapping in the upright SnS_(2).The photoelectric response is higher in the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) heterostructure than in the type-Ⅱ SnS_(2)/Bi_(2)Te_(3) heterostructure due to more efficient charge transportation at the type-Ⅰ SnS_(2)/Bi_(2)Te_(3) heterostructure/electrolyte interface.These results suggest that suitable type-Ⅰ and type-Ⅱ heterostructures can be developed for high-performance photodetectors and other optoelectronic devices.基于新型先进材料的异质结构为提高光电器件的光电性能奠定了基石.能带排列是理解异质结构中载流子输运机理和界面动力学的关键.本文利用物理气相沉积法和化学气相沉积法制备了SnS_(2)/Bi_(2)X_(3)(X=Se,Te)范德华异质结构.通过高分辨率X射线光电子能谱测量的能带排列证实了Ⅰ型SnS_(2)/Bi_(2)Te_(3)和Ⅱ型SnS_(2)/Bi_(2)Te_(3)异质结构的成功制备.基于SnS_(2)/Bi_(2)X_(3)异质结构的光电化学型光电探测器的光电响应得到了极大的提高.Ⅰ型SnS_(2)/Bi_(2)Te_(3)和Ⅱ型SnS_(2)/Bi_(2)Te_(3)异质结构的光电流密度均比SnS_(2)、Bi_(2)Te_(3)和Bi_(2)Te_(3)的光电流密度高一个数量级以上.SnS_(2)/Bi_(2)X_(3)异质结构光电性能的显著提高主要是由于:(i)异质结构中光激发电子和空穴的有效分离;(ii)SnS_(2)/Bi_(2)X_(3)异质结构与电解质界面具有更高的电荷转移效率和载流子密度;(iii)异质结构的构建拓宽了光的吸收范围.此外,直立的SnS_(2)还可以有效地捕获光子以提高其光电性能.Ⅰ型SnS_(2)/Bi_(2)Te_(3)异质结构的光电性能优于Ⅱ型SnS_(2)/Bi_(2)Te_(3)异质结构,这主要源于异质结构/电解质界面上更高效的电荷传输能力.实验研究结果表明,Ⅰ型和Ⅱ型异质结构的构建为开发高性能光电探测器及其他光电器件提供了新思路.

关 键 词：SnS_(2)/Bi_(2)Se_(3) SnS_(2)/Bi_(2)Te_(3) type-Ⅰheterostructure type-Ⅱheterostructure photoelectric response photodetector 

分 类 号：TB34[一般工业技术—材料科学与工程] TN15[电子电信—物理电子学]