UHV thermal evaporation setup and characteristics of ZnSe films grown by UHV thermal evaporation
|摘要:||利用超高真空熱蒸鍍技術，分別於玻璃以及(100)砷化鎵基板上成長硒化鋅薄膜。藉由X-ray繞射以及光激螢光光譜量測來分析薄膜的品質。於ZnSe/Glass上，XRD證實薄膜為高度傾向方向排列的多晶zinc-blend結構；並且估算出薄膜的晶格常數以及晶粒大小分別為 與 。於ZnSe/GaAs上，我們將不同熱處理溫度(505℃隹℃)下所成長的ZnSe/GaAs薄膜，以PL量測分析。發現505℃下成長的薄膜(sample 0719)，有相當明顯的激子結構(I1、I2、FX)，並有因雜質所造成的譜線( )與深層放射光譜分佈(SA band) ；而在585℃下成長的薄膜(sample 0524)，則有因Ga施子與Li或Na等受子復合所造成的DAP放射。此外，藉由XRD光譜，分析不同成長溫度(310℃闎℃)下所成長的ZnSe/GaAs，發現350℃下的薄膜顯然具有較強且半高寬較為狹窄的ZnSe繞射光譜。|
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  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℃.
|Appears in Collections:||Thesis|