Si-Sn-O構造におけるフォトルミネセンスに関する研究

Abstract

Photo-luminescence phenomenon from simultaneous sputtering film of group 4 element and Sn oxide film had been reported. As a result of study on the photo-luminescence characteristic of Si-Sn-O structure film obtained by doping group 4 element Sn to Silicon oxide-film, the photo-luminescence phenomenon was observed by heat treatment of laminated substrates of Sn vapor deposition film. And the photo-luminescence was observed only where Sn concentration was high. To examine this phenomenon, X-ray Photoelectron Spectroscopy (XPS) analysis is inappropriate if the composition varies on the surface. This surface distribution was considered to be Sn condensation caused by the high heat treatment. Therefore the sputtered structure, which enables film lamination at low temperature, was prepared and the photo-luminescence phenomenon was investigated. The device manufacturing process and the experiment methods were explained. As a result of the photo-luminescence measurements of the device made by conventional method and the sandwich structure device by pre- and post-heat treatment, the latter device kept constant characteristic under 700 C and closed to that of the conventional characteristic above 800 C. Also the surface observation by SEM (Scanning Electron Microscope) was carried out. The photo-luminescence peak wavelength of the device by heat treatment up to 700 C was at short wave range, meanwhile that of the device by heat treatment above 800 C was close to the conventional device. Therefore the centers of the photo-luminescence were considered to be different between the sandwich structure and the conventional structure.

4族元素とシリコン酸化膜との同時スパッタ膜から発光現象が報告されている。シリコン酸化膜に4族元素のSnをドープして得られるSi-Sn-O構造膜の発光特性の研究を行ってきた結果、Sn蒸着膜を堆積した基板を熱処理することで、発光現象が確認された。発光はSn濃度の高い場所でのみ生じていた。これら現象を検討するXPS分析は、面内で組成が変化している場合は評価が困難である。この表面分布は高温処理に伴うSnの凝縮と考え、低温で膜堆積が可能なスパッタ構造を作成し発光特性を調べた。その素子作成過程と実験方法について述べた。従来の方法で作成した素子およびサンドイッチ構造素子の熱処理前後におけるフォトルミネセンス測定結果より、今回の素子は700度C以下ではその特性は変化せず、800度C以上で従来の素子特性に近づくことがわかった。またSEMによる表面形状観察を行った。熱処理温度が700度C以下の素子ではフォトルミネセンスのピーク波長が短波長側にあり、800度Cの熱処理では従来素子に近づくため、サンドイッチ構造と従来構造では、発光中心が異なると考えられる。