成長於不同氮化鎵模板之氮化銦鎵多重量子井之光學特性研究

Abstract

半導體發光元件(雷射和發光二極體)在現今的社會有很多的應用，像是雷射指示器、燈號標誌、室內照明以及液晶顯示器。藉由提高半導體發光元件的發光效率，我們可以減少電力上的消耗，所以這是一個重要的研究主題。三族氮化物近年來成為相當熱門的研究材料；但在三族氮化物在磊晶成長的過程當中存在一些無可避免的的問題，如磊晶層與基板間晶格不匹配的現象，造成晶體缺陷的產生與非輻射復合效應增加。 本研究中，將針對上述的情況分別提出解決的辦法。首先在提升晶體品質與降低結構應力方面，分為二個方向探討，一是藉由超晶格結構的缺陷降低機制：使用嵌入氮化銦鎵/氮化鎵超晶格結構；二是晶格匹配的磊晶方式：使用氮化鎵同質磊晶結構。嵌入超晶格結構與同質磊晶結構的使用，確實明顯的降低的磊晶結構的線缺陷密度，同時結構應力也有顯著的改善；針對發光效率進行探討，嵌入超晶格結構之氮化物發光二極體結構內部量子效率約有1.2倍的提升；而同質磊晶結構之氮化物發光二極體結構內部量子效率則具有1.6倍的顯著提高。 在這本論文中，我們提出兩種方法來改善氮化銦鎵/氮化鎵發光結構的發光效率。在第三章和第四章會有對樣品的結晶品質以及光特性有詳細的討論。我們期許相關研究的成果能有助於氮化鎵系列光電元件的發展與進步。

Today, semiconductor light-emitting devices (LASER & LED) have many applications. Such as laser pointer、signal lamp、 indoor lighting and liquid crystal display. By improving the light efficiency of the semiconductor light-emitting device, we can reduce the consumption of the electricity, so it is a important to investigate this issue. The study of the wide bandgap III-nitrides semiconductors recently become a popular investigated topic. However, unavoidable issues existed during the heteroepitaxial growth of III-nitrides semiconductors. Due to the lattice mismatch between the epilayers and substrate, the existence of high defect density resulted in the increase of non-radiactive recombination centers. Therefore, the research attends to improving the light emitting efficiency by using the differnet epitaxial structures. First, the epitaxial structure including the insertion of InGaN/GaN superlattices (SLS) layer have been presented, based on the defect reduction mechanism. Second, homoepitaxial growth of InGaN/GaN structure, based on the lattice matching epitaxy to improve the large lattice mismatch and high defect density. The inserted SLS layer and homoepitaxial growth structures indeed effectively reduce the threading dislocation density and the structural strain. Based on the internal quantum efficiency measurements, the inserted SLS-MQWs structure and the homoepitaxial growth MQWs structure reveal the 1.2-fold and 1.6-fold enhancement respectively. In this thesis, we perform two methods to improve the light efficiency of the InGaN/GaN light emitting structure. The research of the crystal quality and the optical property will be showed in chapter 3 & 4. We expected the outcome of the research could contribute to the development and progress for GaN-based optoelectronic components.