以不同載子生命期調控碲化錳鋅量子點耦合硒化鎘鋅量子井之磁極化子形成機制

Abstract

本論文用分子束磊晶系統成長第二型碲化錳鋅量子點耦合第一型硒化鎘鋅量子井，利用控制硒化鋅中間層厚度為2或5奈米的結構，來調整載子生命週期，以觀察載子生命期長短對磁極化子形成之影響。 我們使用光激螢光光譜並且用不同波長的雷射激發樣品和時間解析光譜來判斷樣品隨著中間層厚度改變，載子的復合路徑變化。由隨著時間演化的光譜中看到譜峰值紅移，其原因包括復合路徑的改變及磁極化子的形成。其中0.1%錳濃度中間層5奈米的碲化錳鋅量子點耦合硒化鎘鋅量子井的樣品中能有效延長載子復合時間，其形成磁極化子的能量也有效增加4至5倍。

In this thesis, type II ZnMnTe quantum dots coupled with type I ZnCdSe quantum well were grown by molecular beam epitaxy (MBE). By controlling the ZnSe spacer layer of 2 and 5 nm, we can adjust the carrier lifetime to study the effect on the magnetic polaron formation. By using photoluminescence (PL) spectroscopy with different laser wavelength and time-resolved PL spectrum, we could identify the change of carrier recombination route in different spacer layer. A red shift of peak energy was observed in the time-dependent PL spectrum, because of the change of carrier recombination route and the magnetic polaron formation. The carrier life time was extended in the sample of 0.1% Mn concentration ZnMnTe quantum dots coupled with ZnCdSe quantum well with 5nm ZnSe spacer layer, the energy of magnetic polaron formation was also enhanced by 4 to 5 times.