利用溫度梯度溶液長晶法成長碲化鋅鎘晶體及其特性之研究

Abstract

本研究係利用溫度梯度溶液長晶法(TGSG)成長碲化鋅鎘塊材晶體並研 究其光聲子的振動模式. 實驗結果發現塊材晶體的光聲子頻率與磊晶的一 樣表現出兩模行為(two-mode be-havior),而且可利用MREI的理論加以描 述,並由之得到重要的物理參數. 另一方面,我們也對碲化鋅鎘塊材晶 體的氧化現象做了初步的分析,得知在長時間空氣的暴露下其表面氧化層 厚度約為100埃,而其主要的氧化物在鋅濃度較低時為二氧化碲;較高時則 為氧化鋅. In this work, we use the temperature gradient solution growth method to growCd1-xZnxTe bulk crystals and study the vibrational modes in the Cd1-xZnxTe bulkcrystals with Raman scattering measurement. The frequencies of Zone-centeroptical phonons of the Cd1-xZnxTe (bulk crystals and epilayers) exhibit two-mode behavior and are well described by the modified random- element isodisplace-ment model. Several important physical parameters are deduced from the fits to the composition dependence of the lattice vibrations. On the other hand, we also have a primitive analysis of the phenomenon of oxidization of Cd1-xZnxTe bulk crystal. We find that the thickness of oxide on the surface of Cd1-xZnxTe is about 100 Angstrom if the sample was put in theair for a long time and the major oxide of Cd1- xZnxTe is TeO2 while the concen-tration of Zn is small and is ZnO while the concentration of Zn is large.