氮化銦鎵發光二極體成長於濕式蝕刻製圖案化藍寶石基板之研究

Abstract

成長在濕式蝕刻製藍寶石基板之氮化鎵發光二極體可提供較佳的 晶格品質並提升較高的光取出效率。濕式蝕刻法除了成本低且可大量製 造，其製造過程中所造成特殊的藍寶石斜面:R 面可提供比乾蝕刻法更高 的光取出。但不可避免的，氮化鎵磊晶層會同時成長在C 面與R 面上。 此兩種成長在C 面與R 面上不同方向的結晶會相互擠壓並於邊界造成線 性差排。此線性差排會逐漸擴大並延伸至元件表面，而造成元件產生漏 電流且抗靜電性變差。在此研究中，我們於濕式蝕刻製藍寶石基板上使 用不同的溫度成長氮化鎵的覆蓋層，並繼續成長成完整的發光二極體結 構，再利用掃描式電子顯微鏡、X 光繞射儀、積分球等量測分析儀器分 析不同溫度下成長氮化鎵的覆蓋層發光二極體的光電特性。於分析結果 中可證明用較低溫度成長氮化鎵的覆蓋層可抑制氮化鎵結晶成長在藍 寶石基板的R 面上。

The GaN LED growth on Wet-etching pattern sapphire substrate ( WPSS ) has provide the high crystal quality and light extraction efficiency.The wet-etching method beside low coast, and lot number fabrication. That will cause the particular inclined plane “ R-plane ” on pattern sapphire for enhance more light extraction compare to Dry-etching method. But inevitably the GaN composition would growth on the C-plane and R-plane at the same time. The different grains on C-plane and R-plane will mutually compress and cause the dislocation among the grains. The dislocation will broaden gradually and extend to the surface of LED, and cause leakage current and ESD fail. In this study, we used the various growth temperature to grow GaN film ( recover layer ) on WPSS. Then continue grown the full structure LED. And analyzed the characterization of the samples growth with various temperatures by SEM, X-rad and EL measurement. According to characterization, we could prove that low growth temperature GaN recover layer could avoid the GaN crystal growth on R-plane.