Dry etching of sapphire substrates and its application for GaN-based light-emitting diodes

• Main Authors: Wen-Chung Shih, 施文忠
• Other Authors: Jau-Shing Fang
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/dmnvjy

碩士 === 國立虎尾科技大學 === 光電與材料科技研究所 === 92 === We have investigated the inductively coupled plasma etching of the sapphire substrate and its application for GaN-based LEDs. First the Ni mask upon the c-face (0001) sapphire substrate was deposited by E-beam evaporation. The etching process was performed under a Cl2/BCl3 (8/12 sccm) gas mixture with a chamber pressure of 3 mTorr. An etch rate of 180 nm/min with a selectivity ratio (sapphire over Ni) of ~6 was achieved under an ICP power of 1200W and a bottom RF power of 350W. The original and patterned sapphire substrates were then used to grow the GaN/InGaN light-emitting diodes (LEDs) by using a metalorganic chemical vapor deposition. Under optimum conditions, the photoluminescence peak intensity was found to enlarge about 50% in magnitude for the LED sample with a patterned sapphire substrate (PSS) at room temperature. These could be attributed to the reduction of threading dislocaion density near the lateral epitaxial growth regions. Furthermore, the light scattering effect by the PSS was also confirmed by the optical simulation result, which improving the light extraction effciency of the GaN LED. It is concluded that the PSS with an optimum design can enhance GaN-based LED performance via both the structure and light scattering improvements.