利用分子束磊晶法成長硒化鋅參錫磊晶層的螢光分析

以分子束磊晶法在半絕緣砷化鎵基板上成長硒化錫鋅磊晶層，利用不同的錫蒸氣分子通量而調變硒化錫銦磊晶層中錫的濃度。藉由能量散佈光譜儀來分析硒化錫銦磊晶層裡錫的濃度，其中最高濃度達到 5.3 原子百分比。我們在低溫反射譜，成長速率圖，和X-Ray散射譜中觀察到在低的錫分子通量下，錫元素扮演表面活性劑以釋放來自於基板所引起的薄膜壓縮應力。藉由變入射角度與表面蝕刻的光激螢光圖譜和原子力顯微鏡中觀察到錫元素在磊晶層中不管是在深度分佈亦或是在磊晶面中會有濃度不均的現象發生，而且，表面處的錫的濃度高於塊材處。在低錫摻雜濃度的螢光中可以看到藍綠色的放光，這藍綠色的放光是由近能隙放光與在2.5500 eV左右寬廣的侷域態放光所組合而成，且從變入射角度與蝕刻樣品表面的光激螢光譜中可以推測這個侷域態放光是與錫元素有關。在低錫摻雜濃度中侷域態放光的較高能量處發現很多銳利且強烈的放光可能歸咎於錫在表面的濃度不均而團聚所產生的原子內部躍遷放光。然而，在高錫摻雜濃度中侷域態與近能隙放光消失了，變成一個在2.7300 eV左右強烈的藍色放光所主宰。且除了最低摻雜濃度的樣品除外，螢光強度因為錫元素的摻雜而增加。

關鍵字

錫；硒化鋅；分子束磊晶；螢光分析

並列摘要

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.

並列關鍵字

Sn-doped ； Zinc Selenide ； Luminescence Analysis ； Molecular Beam Epitaxy

參考文獻

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利用分子束磊晶法成長硒化鋅參錫磊晶層的螢光分析

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