| Summary: | 碩士 === 大同大學 === 光電工程研究所 === 100 === Zn(1-x)SnxSe epilayers were grown on SI-GaAs substrates by molecular beam epitaxy (MBE). The Tin concentration was controlled by varying Tin-cell temperatures. The Tin concentrations, denoted as x with the highest value is 5.3%, are measured by energy-dispersive X-ray spectroscopy (EDX). We observed that Tin plays a role of surfactant to release the strain comes from substrates in low Sn-doped concentration region by low-temperature reflectance, growth rate, and X-ray Diffraction (XRD). Furthermore, the concentration of Tin is not only dependent on the epitaxial depth but also non-uniform near the shallow surface. In photoluminescence spectra of low Sn-doped samples, a blue-green luminescence is combined by near band edge emission and the broad localized states emission at about 2.8000 and 2.5500 eV, respectively. Furthermore, in the incident angle-dependent PL reveals this broad localized states emission is speculated on Tin-related. It is confirmed by the PL of etched samples. Specially, there are lots of sharp and strong emission at the high energy wind of localize state emission, and we guess that this phenomenon is attributed to the atomic inner transition radiation from Tin cluster, which assembling from the non-uniform concentration on surface. However, the emissions in preceding paragraph are not observed in heavy Sn-doped concentration region and a strong blue emission dominated the luminescence at about 2.7300 eV. In addition, the luminescence intensity is enhanced by Sn-doping, except the lowest impurity concentration.
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