Use of Micro-Etching Array to Enhance Light Output Power of GaN-Based Light Emitting Diodes

• Main Authors: Chih-Chen Lai, 賴志成
• Other Authors: Shui-Jinn Wang
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/53208714088035310764

碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 95 === In this thesis, a novel method to fabricate Micro-etching array Vertical-conducting Metal-substrate structure light emitting diode (abbreviated as MVM-LEDs) was demonstrated. The benefits and advancements were reported and discussed as well. Electroplating metal substrates technology was used with patterned laser lift-off (LLO) techniques for the transfer of sapphire substrate onto nickel metal substrates. To enhance the light extraction efficiency of VM-LEDs, the honeycombed micro-hole array were implemented on n-GaN through the use of photo lithography with Inductive Coupled Plasma (ICP) dry etching techniques. The dimensions of honeycombed micro-holes were defined to be with each edge of 4~10 μm with tilted sidewalls. In addition to the increase in the surface emission area, the proposed structure also raises the probability for the light to emit from the surface within the TIR angle. As compared to VM-LEDs of the same size, the electrical characteristics of the fabricated devices are similar, but with an enhancement in light output power by 31% at 20 mA. Furthermore, surface treatments with KOH at 60oC for 60s were made on the n-GaN layer to further improve the light output power. At an injection current of 20 mA, the light output power of the surface treated VM- and MVM-LEDs was 41% and 77% improved respectively as compared to that of regular VM-LEDs.