第二型能帶結構硒化錳鋅/碲硒化鋅多重量子井之長生命期等電性碲束縛激子研究

Abstract

我們利用光激螢光光譜和時間解析螢光光譜分析硒化錳鋅/碲硒化鋅(錳含量佔3以及碲含量佔8莫耳百分比)分析多重量子井結構之光學特性。由隨著雷射功率強度降低與量測到光激螢光光譜峰值紅位移關係以及載子具有較長生命期的特性，證實硒化錳鋅/碲硒化鋅多重量子井能帶排列為第二型式。並從光激螢光變溫光譜實驗分析載子的複合機制，我們發現隨溫度上升(10-260 K)其光譜峰值訊號呈現先紅移再藍移的趨勢(V型位移)，由此表示激子被束縛在較大的侷限能態中。我們也利用變溫時間解析光譜分析載子的複合機制，發現隨著溫度上升，載子生命期呈現先上升後下降的趨勢。因電子位於硒化錳鋅層而電洞位於碲硒化鋅層中被等電性碲原子束縛的能階，故為長距離且複雜的複合路徑，並且此材料結構成功的進一步延長載子生命期。

Carrier dynamics of Zn0.97Mn0.03Se/ZnSe0.92Te0.08 quantum wells was investigated using photoluminescence (PL) and time-resolved PL spectroscopy. Both the power dependence of the PL peak shifts and the long decay time constants confirm the type-II band alignment of the ZnMnSe/ZnSeTe multiple quantum structure. Different recombination paths have been clarified by temperature-dependent measurements. The PL peak energy exhibits a V-shaped dependence on temperature (10 – 260 K), which indicates strong carrier localization. Additionally, the PL lifetime initially increases and then monotonically declines as the temperature increases. The long-range recombination between the electrons in ZnMnSe and the holes trapped by the isoelectronic Te states in ZnSeTe complicates the decay traces and prolongs the exciton lifetime further.