Electro-Optical Properties of InAs/GaAs Quantum Dots

• Main Authors: Jia-Ren Lee, 李佳任
• Other Authors: Chien-Rong Lu
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/92621321968287667767

碩士 === 國立臺灣師範大學 === 物理研究所 === 89 === ABSTRACT The electro-optical properties of InAs/GaAs Quantum Dots have been studied by comparing the photoreflectance and photoluminescence spectra at various temperatures. The samples used in our experiments were grown by Metal-Organic Chemical Vapor Deposition on the n+ dopped GaAs substrates. The photoreflectance spectral features below the energy gap of GaAs originate from the InAs wetting layer , and the relative spectral intensity between the InAs wetting layer and the GaAs energy gap increases with the decreasing of temperature . The photoluminescence spectral profiles consist of contributions from the equal spacing energy levels of the InAs quantum dots, and agree with the prediction of the disc-shaped quantum dots theoretical calculations. The red shifts of the quantum dots energy levels with the increasing temperature may be influenced by the internal electric fields induced Stark effect. Since the quantum dots transitions were observed in the photoluminescence spectra and the wetting layer transitions were observed in the photoreflectance spectra, we propose that the Fermi level of the system is located between the highest energy level of the wetting layer and the lowest energy level of the quantum dots.