CdSe/CdZnSe超晶格的激子光学性质的研究

用分子束外延法在GaAs衬底上生长了CdSe/Cd0.65Zn0.35Se超晶格结构。利用X射线衍射（XRD）、77K下变密度激发的光致发光光谱和变温度光致发光光谱研究了CdSe/CdZnSe超晶格结构和激光复合特性，在该材料中观测到激子－激子散射发射峰，变密度激发光致发光光谱和谱温度光致发光光谱证实了这一现象，激子发射峰的线宽随着温度的升高而展宽，低温时发光峰的宽度主要是由合金组分和阱垒起伏引起的，没温时激子线宽展宽是由于激子与纵光学声子和离化的施主杂质间的散射作用引起的，光致发光的强度随着温度的升高而降低，这主要是由激子的热离化造成的，也就是说，热激发使得电子或空穴由阱中跃迁至垒上。

Exciton Optical Properties of CdSe/CdZnSe Superlattices

CdSe/Cd 0.65Zn 0.35Se superlattices were grown by molecular beam epitaxy on substrate GaAs. The structure and exciton optical properties in high quality CdSe/CdZnSe superlattices are investigated by means of XRD spectra, photoluminescence spectra with different excitation power at 77 K and photoluminescence spectra with different temperature. The emission peak from exciton-exciton scattering is observed in CdSe/CdZnSe superlattices. It is validated by photoluminescence spectra with different excitation power and different temperature. The linewidth of the exciton emission becomes broader with increasing temperature. The linewidth at low temperature is due to the alloy composition and well thickness fluctuations, and the linewidth broadening at high temperature is contributed by the interactions among the exciton and LO phonons and ionized donor impurities. The photoluminescence intensities are reduced with increasing temperature, which is mainly due to the thermal dissociation of excitons, i. e., the electrons or holes jump from the wells into the barriers by thermal excitations.