藉著在不同軸向藍寶石基板上使用不同圖案化來提升氮化鎵之發光二極體的結晶品質與性能

Abstract

本論文主旨為探討修改圖案化藍寶石基板表面來增進氮化鎵發光二極體（GaN-Based Light-Emitting Diode，GaN-LED）表現以及使用不同軸向基板達到藍寶石晶體的利用率的結果探討。 在修改的濕式蝕刻之圖案化基板對於氮化鎵二極體發光功率影響的實驗中，我們發現在利用濕蝕刻製作之圖案化藍寶石有幾個側面的斜面，此斜面容易在磊晶氮化鎵時出現閃鋅礦(zincblenda)結構，利用BCl3為基礎的電漿轟擊此表面之後不只可以抑制閃鋅礦結構的出現，並且可以提升發光二極體的亮度。此外”OPSS”是此在金字塔頂部蓋一層氧化物於頂部c面的圖案化基板，可以發現OPSS的輸出能量為29 mW，較傳統的PSS高了6.2 %。 A軸PSS的研究將發展高晶體利用率進而得到較便宜的氮化鎵發光二極體基板，”ALPSS”是週期性線條式的圖案於a平面基板上，在製作成氮化鎵發光二極體後輸出能量為9.1 mW，比平片增加59.6 %，主要是因為磊晶品質的提升與光取出效率的增加。 利用兩次蝕刻方式，在a平面基板上製作週期性似帳篷的點狀圖案化，此稱為ADPSS於氮化鎵發光二極體發現輸出電壓為9.6mW，比較於a平面基板更68.4 %。

The primary objective of this dissertation is to improve performance of GaN-based LEDs by using various pattern sapphire substrates and to increasing ratio of the sapphire boule was utilized by using different axis sapphire. In the investigation, modify wet-etching pattern sapphire substrates have been used to grow GaN-based LEDs. However, after wet etching, several sidewall facets were exposed on the patterns of PSS. These sidewall facets would grow zincblende GaN and form irregular voids. BCl3-based plasma was used to solve this problem and improve the performance of GaN-based LEDs. Besides, “OPSS” was pyramid array PSSs with an oxide-covered top c-plane. It was found that the output power of OPSS was 29.0 mW, which was 6.2 % higher than that of CPSS. An investigation of the a-axis PSS has led to the development of a low cost substrate. A-plane sapphire substrates were used to grow GaN LEDs. “ALPSS” was a-plane with periodic line array pattern. It was found that the output power of ALPSS-LED was 9.1 mW, which was 59.6 % larger than the AFlat-LED at an injection current of 20 mA. This is because GaN crystal quality and light extraction efficiency of ALPSS-LED were better than those of AFlat-LED. Periodic tent-like dot patterns on a-plane sapphire substrates were fabricated using two steps etching process. They were denoted as ADPSS. Compared with the GaN-based LED grown on a-plane sapphire without any pattern (AFlat), the ADPSS-LED has higher output power, light extraction efficiency and external quantum efficiency, and better crystal quality. The output power of ADPSS-LED was 9.6 mW, which was 68.4 % larger than the AFlat-LED. Besides, the blue shift of ADPSS-LED was found to be less than that of AFlat-LED.