Open Access Nano Express

Extended photoresponse and multi-band luminescence of ZnO/ZnSe core/shell nanorods

Qin Yang13, Hua Cai1, Zhigao Hu2, Zhihua Duan2, Xu Yang1, Jian Sun1, Ning Xu1 and Jiada Wu1*

Author Affiliations

1 Department of Optical Science and Engineering, Fudan University, Shanghai 200433, China

2 Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241, China

3 College of Science, Guizhou Minzu University, Guiyang 550025, China

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Nanoscale Research Letters 2014, 9:31  doi:10.1186/1556-276X-9-31

Published: 15 January 2014

Abstract

Aligned ZnO/ZnSe core/shell nanorods (NRs) with type-II energy band alignment were fabricated by pulsed laser deposition of ZnSe on the surfaces of hydrothermally grown ZnO NRs. The obtained ZnO/ZnSe core/shell NRs are composed of wurtzite ZnO cores and zinc blende ZnSe shells. The bare ZnO NRs are capable of emitting strong ultraviolet (UV) near band edge (NBE) emission at 325-nm light excitation, while the ZnSe shells greatly suppress the emission from the ZnO cores. High-temperature processing results in an improvement in the structures of the ZnO cores and the ZnSe shells and significant changes in the optical properties of ZnO/ZnSe core/shell NRs. The fabricated ZnO/ZnSe core/shell NRs show optical properties corresponding to the two excitonic band gaps of wurtzite ZnO and zinc blende ZnSe and the effective band gap between the conduction band minimum of ZnO and the valence band maximum ZnSe. An extended photoresponse much wider than those of the constituting ZnO and ZnSe and a multi-band photoluminescence including the UV NBE emission of ZnO and the blue NBE emission of ZnSe are observed.

Keywords:
ZnO/ZnSe core/shell nanorods; Type-II heterojunction; Photoresponse; Near band edge emission; Suppression of luminescence