砷化銦單量子點藉應力以及磁場調變精細結構分裂

Abstract

砷化銦單量子點具有精細結構分裂，源於其量子點本身形狀之不對稱。本文透過Bir-Pikus漢米爾頓方程式來探討精細結構分裂。外加水平磁場改變激子能態精細結構分裂，從而探討能態可否藉此調控回簡併的原因以及條件。藉由外加應變於量子點的方式同時調變其精細結構分裂以及本徵軸。實驗顯示在外加應力的輔助下，激子精細結構分裂反交叉的程度有被改善。故此說明同時結合外加應力以及水平磁場的方式，是有可能將單量子點的激子能態調併回簡併態。

The fine structure splitting (FSS) of exciton emissions from single InAs/GaAs quantum dots (QDs) are investigated. The excitonic FSS is attributed to the QD shape asymmetry reduction. Through the formulism of the Bir-Pikus Hamiltonian, the relationship between the FSS and strain is discussed. The excitonic FSS can be manipulated by applying in-plane magnetic field. We have discussed the reason that causes anti-crossing of the two bright exciton state. By applying external stress, the FSS and the eigenaxes of QDs can be changed simultaneously.In the experiment, the degree of anti-crossing do improved under external stress assistance.By combining these two methods, the single quantum dot excitonic state can be recovered to degeneracy