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Optical characterization of type II Zn0.97Mn0.03Se/ZnSe0.92Te0.08 multiple-quantum-well structures

Der-Yuh Lin 1Jian-Jhin Shiu 1Jun-De Wu 1Wei-Li Chen 1Chu-Shou Yang 2Wu-Ching Chou 2

1. Department of Electronic Engineering, National Changhua University of Education, 1, Jin De Road, Changhua City, Changhua 50007, Taiwan
2. Institute and Department of Electrophysics, National Chiao-Tung University, 1001, Ta Hsueh Road, Hsinchu 30050, Taiwan

Abstract

Recently some spin injectors and spin aligners, consisting of II-VI compound diluted magnetic semiconductor heterostructures as well as III-V compound semiconductor heterostructures, have been fabricated. Spintronics has attracted a good deal of attention owing to its potential applications in quantum computation, as well as its interesting physical properties of its building materials. In this paper, we present the interesting optical properties of ZnMnSe/ZnSeTe multiple-quantum-well (MQW) structures using photoluminescence (PL) and photoreflectance (PR) measurements. We prepared two sets of Zn1-xMnxSe/ZnSe1-yTey(x=0.03,y=0.08) MQW samples grown on GaAs substrate by molecular beam epitaxy (MBE). For the samples A, B and C (D, E and F), the thickness of the ZnSeTe (ZnMnSe) layers is fixed at 20nm and the thickness of ZnMnSe (ZnSeTe) layers is varied among 5, 3 and 1 nm, respectively. PL data reveal that the band alignment of the ZnMnSe/ZnSeTe system is type II. Comparing with the theoretical calculation based on the Schrodinger equation, the valence band offset can be estimated. From the power-dependent PL spectra, it is observed that the peak position of PL spectra shows a blueshift under different excitation power. This effect can be interpreted in terms of the band-bending and band-filling effects due to the spatially photoexcited carries in a type-II aligment. We also found that the PL spectra exhibit a large in-plane polarization with the polarization degree up to 50%. The polarization does not depend on the excitation intensity as well as temperature, which excludes the possibility of extrinsic mechanisms related to the in-plane anisotropy. Photoreflectance has been widely used to investigate the intersubband transitions. In this study, for PR spectra the optical features corresponding to the ground and excited state transitions are found and discussed.

 

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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium F, by Der-Yuh Lin
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-15 14:54
Revised:   2009-06-07 00:44