氧碲化鋅高度不匹配半導體之中間能帶光學特性研究

Abstract

本研究藉由光激發螢光光譜與時間解析光譜來探討氧碲化鋅高度不匹配半導體之光學特性。我們利用分子束磊晶系統成長在碲化鋅基板上不同氧含量的高度不匹配氧碲化鋅半導體，氧含量分別為0.43%、0.77%以及 1.09%。由於氧團簇或合金成份不均勻所造成載子侷域化效應主導整個PL圖譜和多峰訊號的結果。隨著氧含量增加，PL訊號向較低的能量移動。上述的實驗結果和描述碲化鋅導帶與氧的缺陷能帶互斥而分裂較低的次能帶(E-)緊密地相關。此外，隨著氧含量的增加，氧碲化鋅的生命期與衰減情形展現出複雜的行為。我們透過使用不同的激發能量與變溫相關的測量來驗證這衰減的復合機制。

Optical properties of the highly mismatched ZnTeO semiconductors (O = 0.43, 0. 77, and 1.09 %) grown on ZnTe substrates by molecular beam epitaxy were studied using photoluminescence (PL) and time-resolved PL spectroscopy. The carrier localization caused by O clustering or alloy fluctuations dominates the entire PL spectra and results in multi-peak structures. As the O concentration increases, the PL emissions shift toward lower energies. These experimental results correlate well with the lower (E-) conduction subband, resulting from the anticrossing interaction between the O defects and the extended conduction states of ZnTe. Additionally, the PL lifetime of ZnTe1-xOx increases with increasing O contents and the decay curves exhibit complex behavior. The decay dynamics is clarified by using different excitation energy and temperature-dependent measurements.