二維過渡金屬二硫族化物之間能量轉移之理論研究

Abstract

半導體是一切科技發展的基礎，不論電腦科技或自動化控制發展得多麼厲害，終究需要利用半導體為載體，以實現在現實生活中的運用。而半導體技術的發展，奠定於對操控電子能力的掌握程度。 近年來，隨著二維材料的發展，二維半導體的重要性也逐漸被發掘。和傳統半導體材料相比，二維半導體中的電子多了能谷自由度，讓我們能透過能谷操縱電子進行編譯或儲存資訊，因此對能谷物理的掌握程度是當今的一大課題。 而二維半導體激子的發光，是最容易能表現出能谷物理特性的管道。只要我們能夠掌握二維半導體激子的發光過程，就能對二維半導體的能谷物理有更深入的了解。 本篇論文由k ⋅ p二能帶模型出發，描述二維半導體能谷附近的電子結構，再搭配激子理論，推導出具有特殊光學選擇率的能谷激子波函數，並計算K 與K’能谷間的激子交換能，以建立出一套完整的二維半導體激子理論模型。並以此理論模型為基礎，利用Lindblad master equation 去分析單層及兩層單層二維半導體之間的能量的傳遞過程和能谷態的動態演化行為。

Over these years, the potential of 2D semiconductor has been discovered progressively because of the extra valley degree of freedom. It could bring us fully novel concept. The valley properties can be studied thought the exciton radiative emission easily. If we want to know about the physics of valley, grasping the process of the exciton radiation is an appropriate method. In this thesis, we discuss the valley-dependent exciton and the long-range exciton inter-valley exchange energy in monolayer TMDs. Our formalism combines the TMDs electron band structure near valley with a many-body Bethe-Salpeter equation treatment of the electron-hole interaction. We show analytically that the single-particle, valley-dependent selection rules are preserved in the presence of excitonic effects. Based on this theory, we use Lindblad master equation to study the exciton dynamics, which is affected by energy transfer and valley transfer between two monolayers TMDs.