以氫化物氣相磊晶法成長氮化鎵厚膜之陰極螢光特性分析

Abstract

本論文利用陰極螢光系統和掃描式電子顯微鏡研究氮化鎵厚膜之側面發光情形，而氮化鎵厚膜是由氫化物氣相磊晶法在藍寶石基板(Al2O3)上製備而成的，由於異質磊晶會造成樣品缺陷密度過高，對於往後製造發光元件上有許多不利之處，所以採用目前廣為大家所使用的ELOG技術，以降低缺陷密度，但是在側面的陰極螢光圖形中，會有規律的發光圖案，然而此發光圖案在文獻中仍未有清楚而明確的解釋，因此，解釋此現象正是本論文的主題，不僅於此，本文中還針對另一種成長方式：Pendeo，來和傳統的ELOG側面發光情形做比較，而Pendeo又可細分為數種不同的填充因子(fill factor)，並討論Pendeo成長方式的機制和品質高低，再利用陰極螢光和原子力顯微鏡計算缺陷密度，加以比較，證明陰極螢光系統在計算缺陷密度方面和原子力顯微鏡搭配蝕刻缺陷密度有相同的能力。

In the present day, we use epitaxial lateral overgrowth (ELOG) technique to reduce defect densities on the surface of the GaN bulks. It is mystical that there are lots of regular luminescence patterns on the side of these GaN bulks by using the cathodoluminescence (CL) spectrometer and scanning electron microscope (SEM). However, there is still no one can explain how these regular patterns happened. Therefore we don’t only analyze the angles and shapes of these patterns but also adjust the fill factors and conditions of the epitaxial process. Besides, we use pendeo epitaxy (PE) technique to grow GaN bulks on sapphires and do the same works at the ELOG technique. In the end, we know that luminescence patterns may have relation to directions of the lithography process and find some curious optical characteristics in CL spectrums and images.