以激發相干技術研究氮化銦之載子動力學

Abstract

本論文以激發相干技術研究載子濃度對氮化銦薄膜載子動力學的影響。我們利用激發相干技術量測不同退火溫度之氮化銦樣品，並分析譜線受填態效應與交互複合非線性效應的影響。由低溫激發相干譜線得知在低載子濃度樣品中，其交互複合效應比高載子濃度樣品明顯。藉由變功率量測不同載子濃度樣品之低溫激發相干光譜，可辨認出在低載子濃度樣品中，其交互複合項受熱載子效應影響而寬化。藉由量測不同發光能量之低溫激發相干時間解析光譜，可得知高(低)載子濃度在價電帶尾形成較高(低)的侷限能量。透過變溫螢光光譜及時間解析實驗，可分析出各溫度輻射及非輻射性生命期對複合機制的貢獻。觀察實驗結果並以帶間躍遷複合理論模擬輻射性生命期隨溫度的關係，得知輻射性生命期在低溫中受侷限能影響而變慢，並隨著溫度增加脫離束縛而轉換成帶間躍遷複合發光。

The effects of carrier concentration on the carrier dynamics in InN is investigated by time-resolved excitation correlation. We know that the band-filling and cross-correlation contribute to the excitation correlation spectrum. We observe the cross-correlation effect in low carrier concentration which is obvious than high carrier concentration. With the varying excitation power, the hot carrier effect affects the broadening of cross-recombination in low carrier concentration. We obtain the high/low localized energy due to high/low concentration which is studied by the energy-dependent time-resolved excitation correlation (TREC) spectra. With temperature-dependent PL and TREC, we can analyze the radiative and non-radiative lifetime at different temperature. The carrier localization at low temperature retards the radiative lifetime which is compared with the simulation of band-to-band recombination theory. And the increasing temperature will transform radiative lifetime into band-to-band recombination.