以分子束磊晶法成長氧化錳鋅稀磁性半導體的磁學與光學特性

Abstract

本研究利用分子束磊晶方法將高品質的氧化錳鋅薄膜成長於以氮化鋁作為緩衝層的矽(111)基板上，並藉由光激螢光系統及超導量子干涉儀等方法量測成長出的氧化錳鋅薄膜在不同錳濃度下的光學與磁學特性並進行分析。 從光激螢光光譜中可以確認氧化鋅薄膜具有良好的發光特性，並且能觀察到激子復合發光會隨著錳濃度上升而急遽減弱，同時也因此可在較高錳濃度的樣品中觀察到共振拉曼現象，並可以瀑布模型解釋不同訊號峰值的強度變化。 而從室溫磁滯曲線中可發現不同濃度下的氧化錳鋅樣品皆具有室溫鐵磁性，其中也包括了未進行錳摻雜的純氧化鋅樣品，對此我們採用束縛磁極化子模型來描述不同樣品中的磁性行為，並推測氧化鋅樣品中的鐵磁性可能由缺陷誘發

This research is dedicated to the growth of high quality ZnMnO thin films on Si(111) substrates with AlN as buffer layer by molecular beam epitaxy (MBE). The optical and magnetic properties were investigated by photoluminescence (PL) system and superconducting quantum interference device (SQUID). The PL spectra confirmed good emission property in ZnO sample, and the quench of excitonic transitions as Mn doping concentration increased was observed. Hence the resonant Raman scattering phenomenon became clear in samples with higher Mn doping concentration and the intensity variation of different peaks could be explained by cascade model. Room temperature magnetic hysteresis loops indicated the existence of room temperature ferromagnetism in all ZnMnO samples including ZnO. Bound magnetic polaron model is employed to describe the distinct magnetic properties in ZnMnO samples and the ferromagnetism in ZnO could be inferred that is induced by defects.