銅銦鎵硒薄膜的超快時間解析研究

Abstract

首先以光致螢光偵測系統量測靜態螢光光譜，銅銦鎵硒薄膜樣品(1)至(3)的螢光光譜分別由 CIGS、缺陷 Cd_Cu (鎘取代銅原子的位置)與 V_Cu (銅原子的位置空缺)所造成，以及樣品(1)至(4)對應銅銦鎵硒缺陷模型的可能螢光機制為 D 躍遷至 A2 或 A1 的施會-受體復合；光致螢光升頻系統的最小時間解析度約 140 fs。由激發-探測了解在皮秒尺度下載子的動態行為，透過時間延遲相關瞬時反射率變化ΔR/R 得知鎘置換銅的位置 Cd Cu 與銅空缺 V Cu 所造成的快的衰減常數τ 1 分別為 0.51±0.03 及 0.53±0.01 ps；以及慢的衰減常數τ 2 ，對銅銦鎵硒薄膜樣品(1)、(3)與(4)大約為 20 ps。 從光致螢光偵測系統的靜態螢光光譜了解螢光放光範圍及強度的基本特性，透過TRFL 系統量測奈秒尺度的時間解析螢光光譜；由激發-探測得到的皮秒尺度的瞬時反射率變化ΔR/R，以及運用光致螢光升頻系統將螢光的時間解析延伸至飛秒等級的時間尺度，來更清楚了解樣品內部載子的動態運動行為。

Make use of Photoluminescence detection system to measure stationary fluorescence spectra, CIGS thin film, sample (1) to (3) correspond to CIGS、Cd_Cu and V_Cu,respectively. Comparing with CIGS defect model, the other possible transition mechanisms are D transition to A2 or D transition to A1 (donor-acceptor recombination) for sample (1) to (4). The minimum time resolution of photoluminescence up-conversion system is about 140 fs. From the pump-probe measurement, we acquire the carriers dynamics in picosecond region. Delay time dependence of normalized reflectance change ΔR/R, the fast decay time constantτ 1 due to Cd atom substitutes Cu position Cd_Cu and vacancy in Cu position V_Cu are 0.51±0.03 and 0.53±0.01 ps,respectively. Furthermore, CIGS thin film samples (1)、(3) and (4) have slow decay time constant τ2 about 20 ps. From photoluminescence detection system, we obtain the basic property of fluorescence intensity and region. Utilize TRFL system to measure nanosecond time-resolved fluorescence spectra. The pump-probe technique is able to measure picosecond delay time dependence of normalized reflectance change ΔR/R. By means of photoluminescence up-conversion system extends to femtosecond scale. In this manner, try to understand carriers behaviors’clearly.

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