Tunable Band Gap and Conductivity Type of ZnSe/Si Core-Shell Nanowire Heterostructures

Yijie Zeng; Huaizhong Xing; Yanbian Fang; Yan Huang; Aijiang Lu; Xiaoshuang Chen

doi:10.3390/ma7117276

Tunable Band Gap and Conductivity Type of ZnSe/Si Core-Shell Nanowire Heterostructures

Materials (Basel). 2014 Oct 31;7(11):7276-7288. doi: 10.3390/ma7117276.

Authors

Yijie Zeng¹, Huaizhong Xing², Yanbian Fang³, Yan Huang⁴, Aijiang Lu⁵, Xiaoshuang Chen^{6

4}

Affiliations

¹ Department of Applied Physics and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Ren Min Road 2999, Songjiang District, Shanghai 201620, China. dhu_zyj@mail.dhu.edu.cn.
² Department of Applied Physics and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Ren Min Road 2999, Songjiang District, Shanghai 201620, China. xinghz@dhu.edu.cn.
³ Department of Applied Physics and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Ren Min Road 2999, Songjiang District, Shanghai 201620, China. fangyanbian@163.com.
⁴ National Lab of Infrared Physics, Shanghai Institute for Technical Physics, Chinese Academy of Science, 500 Yu Tian Road, Shanghai 200083, China. yhuang@mail.sitp.ac.cn.
⁵ Department of Applied Physics and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Ren Min Road 2999, Songjiang District, Shanghai 201620, China. ajlu@dhu.edu.cn.
⁶ Department of Applied Physics and State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Ren Min Road 2999, Songjiang District, Shanghai 201620, China. yhuang@mail.sitp.ac.cn.

Abstract

The electronic properties of zincblende ZnSe/Si core-shell nanowires (NWs) with a diameter of 1.1-2.8 nm are calculated by means of the first principle calculation. Band gaps of both ZnSe-core/Si-shell and Si-core/ZnSe-shell NWs are much smaller than those of pure ZnSe or Si NWs. Band alignment analysis reveals that the small band gaps of ZnSe/Si core-shell NWs are caused by the interface state. Fixing the ZnSe core size and enlarging the Si shell would turn the NWs from intrinsic to p-type, then to metallic. However, Fixing the Si core and enlarging the ZnSe shell would not change the band gap significantly. The partial charge distribution diagram shows that the conduction band maximum (CBM) is confined in Si, while the valence band maximum (VBM) is mainly distributed around the interface. Our findings also show that the band gap and conductivity type of ZnSe/Si core-shell NWs can be tuned by the concentration and diameter of the core-shell material, respectively.

Keywords: ZnSe/Si core-shell; conductivity type; interface states; nanowires; tunable bandgap.