石墨烯的SdH振盪

Abstract

石墨烯在最近十年成為最為熱門的二維材料。其傳輸性質受到半導體界的重視，期待能夠控制並製作出高效能與低功耗元件。雖然石墨烯的理論與實驗漸趨完備，惟實驗系統的設置有其複雜性，且介觀物理實驗至今仍是大宗，還有許多討論的空間。像是對石墨烯作參雜（doping）、改變應力（strain）、或是含有缺陷（defect）等多種實驗方法，在物理化學性質都出現變化。本論文利用 Landauer-Keldysh 方程結合非穩態格林函數（NEGF）運算模擬實驗，透過考慮引入無序系統（disordered system）及線缺陷（line defect），試圖探討石墨烯在高磁場下的量子霍爾效應（Quantum hall effect）及電阻呈現變化的 Shubnikov-de Hass （SdH）振盪。

Graphene is a well-known two-dimensional material. Recently, researchers pursuit in developing controllable method to tune the properties of graphene in order to make it prior to existing product in semiconductor industry. Substitution of graphene such as N-doped graphene shows interesting properties compared with pristine graphene. The quantum hall effect can be presented for pristine graphene devices in lots of experiments. While N-doped graphene displays a different phenomena under high external magnetic field, the magneto-resistance (MR) appears to have enhanced the Shubnikov-de Hass (SdH) oscillation but decrease the oscillation frequency. The thesis focus on the transport properties and also SdH oscillation for graphene constructed by tight binding model and discuss the physical phenomena while considering disordered potentials or line defects. The transport properties are analyzed by the Landauer-Keldysh formalism by using non-equilibrium Green function (NEGF) technique.