Observation of strong anisotropic forbidden transitions in (001) InGaAs/GaAs single-quantum well by reflectance-differen
- PDF / 632,737 Bytes
- 10 Pages / 595.276 x 793.701 pts Page_size
- 10 Downloads / 168 Views
NANO EXPRESS
Open Access
Observation of strong anisotropic forbidden transitions in (001) InGaAs/GaAs single-quantum well by reflectance-difference spectroscopy and its behavior under uniaxial strain Jin-Ling Yu, Yong-Hai Chen*, Chen-Guang Tang, ChongYun Jiang, Xiao-Ling Ye
Abstract The strong anisotropic forbidden transition has been observed in a series of InGaAs/GaAs single-quantum well with well width ranging between 3 nm and 7 nm at 80 K. Numerical calculations within the envelope function framework have been performed to analyze the origin of the optical anisotropic forbidden transition. It is found that the optical anisotropy of this transition can be mainly attributed to indium segregation effect. The effect of uniaxial strain on in-plane optical anisotropy (IPOA) is also investigated. The IPOA of the forbidden transition changes little with strain, while that of the allowed transition shows a linear dependence on strain. PACS 78.66.Fd, 78.20.Bh, 78.20.Fm Introduction It is well known that in-plane optical anisotropy (IPOA) can be introduced in a (001)-grown zinc-blende quantum well (QW) when the symmetry is reduced from D2d to C 2υ [1-6]. There are two kinds of symmetry reduction effect (SRE), one is bulk SRE, and the other is interface SRE [2,4]. The bulk SRE can be introduced by electric field, compositional variation across the QW and uniaxial strain [7-10]. The IPOA induced by uniaxial strain in GaAs/AlxGa1-xAs QWs has been reported by Shen [10], Rau [8] and Tang [11]. However, as far as we know, this effect in InxGa1-xAs/GaAs QW has never been reported. The interface SRE, which origins from C2υ symmetry of a (001) zinc-blende interface, can be introduced by special interface chemical bonds, segregation effect and the anisotropic interface structures [2,3,6]. It was found that the interface-induced IPOA was very strong in the QWs sharing no-common-atom, while the IPOA in QWs sharing common atoms such as GaAs/AlGaAs was too weak to be observed by conventional polarized spectroscopy [2,4,10]. Fortunately, the weak IPOA in the AlGaAs/ * Correspondence: [email protected] Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, People’s Republic of China
GaAs and InGaAs/GaAs QWs can be well observed by the reflectance-difference spectroscopy (RDS) [2,4,6]. Wang et al. has studied forbidden transitions in InxGa1x As/GaAs by photoreflectance (PR) and attributed the forbidden transition to the built-in electric field [12]. Chen et al. [1] and Ye et al. [6] observed anisotropic forbidden transition in In x Ga 1-x As/GaAs by RDS. Chen ascribed the anisotropic forbidden transition to the interplay of interface C2ν symmetry and built-in electric field, while Ye attributed it to both the built-in electric field and segregation effect. In this study, we observed strong anisotropic forbidden transitions in a series of In xGa1x As/GaAs single-quantum well (SQW) with well width ranging between 3 nm and 7 nm at 80 K. Numerical calculat
Data Loading...
