【摘要】 报道了GaAs-AIAs多量子阱(MQW)结构的室温光调制反射(PR)光谱。与2K下光荧光激发谱的对比表明室温下激子作用的重要性。讨论了GaAs-AlAsMQW结构的PR调制机制,指出它仍可能是表面电场调制,但不同于体材料的情形,而是具有一阶微商本质,并且在弱场条件下以量子化子带及相应激子带隙的斯塔克移动的调制为主。更多还原

【Abstract】 Photoreflectance (PR) spectra of GaAs AlAs multiple quantum well (MQW) structures at room temperature are measured and compared with the photoluminescence excitation spectrum at 2K. The results show that the excitonic process is very important for GaAs-AlAs MQWs even at room temperature. The PR modulation mechanism of GaAs-AlAs MQW structures is discussed. It is pointed out that the PR modulation is mainly caused by the optical modulation of the surface electric field. In contrast to the case of bulk materials, the PR spectra of MQWs have mainly the first derivative functional lineshapes. Under the low field condition, they are dominated by She stark shifts of quantized subbands and corresponding excitonic energy gaps.更多还原