| Summary: | 碩士 === 國立交通大學 === 物理研究所 === 89 === ZnSe thin films were grown on glass and (100) GaAs substrates by thermal evaporation in UHV situation. X-ray diffraction and photoluminescence measurements are employed to analyze the quality of the grown films.
XRD confirmed that the film grown on the glass substrate is in zinc-blende polycrystalline structure with high orientation in [111] direction； the lattice constant and the grain size were estimated to be and , respectively.
Photoluminescence(PL) measurements were used to study the property of these films, such as chemical impurities and native defects in the ZnSe /GaAs films with which GaAs substrates were outgassed at 505℃(sample 0719) and 585℃(sample 0524), respectively before ZnSe films were grown on these substrates. The spectrum of sample 0719 shows a rich excitonic structure associated with neutral donor-bound excitons I2, neutral acceptor-bound excitons I2 and free excitons FX, and the peaks related to impurities involving the line and the deep level emission SA. The peak in PL spectra at ~2.7eV was observed only for the sample 0524, it is believed that this peak is associated with donor-acceptor transitions which originated from the radiative recombination between a Ga donor and a contaminated Li and Na acceptor.
ZnSe/GaAs films with different grown temperatures (310℃闎℃) were characterized by DCXRD. We discovered that the films grown at 350℃ showed the stronger ZnSe peak with a smaller FWHM value than that grown at 310℃.
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