氯化鈉在鍺表面上的長晶過程

Abstract

本論文是研究氯化鈉在鍺(100)表面上的長晶過程。實驗方法是以同步輻射光為光源，透過觀測Ge 3d、Na 2p、Cl 2p以及氯化鈉價電帶的X光光電子激發能譜，以便了解樣品表面的原子結構。在交疊成長氯原子與鈉原子於鍺表面的過程中，會讓表面電位產生變化，出現能帶偏移(Band-Offset)的現象。我們於超薄的氯化鈉絕緣層上方，吸附滿氯原子之後，這時表面電荷密度提高，而接面上鍺原子的電荷密度降低，氯化鈉能帶因此產生能帶偏移。能帶偏移幅度為1.66 eV ~ 1.76 eV。接著，於表面上再度成長鈉原子後，會讓表面電荷回到中性，能帶也因此回到了原始的狀況。

This thesis describes the atomic layer epitaxy of NaCl on Ge(100) surface. The experimental method employed is the high-resolution X-ray photoemission spectroscopy using synchrotron radiation as the photon source. Photoelectron spectra from the Ge 3d, Na 2p and Cl 2p core levels and from the NaCl valence band have been analyzed for the growth NaCl crystals. We can observe the NaCl band-offset when growing Cl and Na atoms alternately. Chlorine termination of NaCl ultra-thin film can increase the charge density on the surface, leading to the NaCl band offset. The valence band offset ranges from 1.66 ~ 1.67 eV. Finally, when evaporating about 1.2ML of the Na atoms on the surface. The surface returns to charge neutrality, and the bands become flat again.