High Efficiency GaN Light Emitting Diodes Device by Photoelectrochemical technology

• Main Authors: Zhong-Jie Yang, 楊仲傑
• Other Authors: Chia-Feng Lin
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/8pap98

碩士 === 國立中興大學 === 材料工程學系所 === 94 === In this thesis, the Nitride-based light emitting diodes with a mesa sidewall roughening process to increase light output power have been study. The fabricated GaN-based LED wafers were treated through a photoelectrochemical (PEC) process. The Ga2O3 layer was formed around the GaN:Si n-type mesa sidewalls and the bottoms mesa etching regions. Selective wet oxidation was occurred at the mesa sidewall between the p- and the n-type GaN interface. The light output power of the PEC treated LED had 42% enhancement (10V/10min) which was caused by a reduced index reflectance of GaN/Ga2O3/air layers, roughen Ga2O3 surface, microroughen GaN sidewall surface, and a selective oxidation step profile of the mesa sidewall to increase the light-extraction efficiency from the mesa sidewall direction. The InGaN-based light emitting diode (LED) with an inclined undercut structure is fabricated through the photoelectrochemical two-step process to increase light extraction efficiency. The first step is created undercut structure by selective wet oxidation on n-type GaN occurred at p-n GaN interface on mesa sidewall in pure H2O solution. The second step is formed inclined undercut structure through a crystallographic wet etching process by immersing in hot KOH solution. This crystallographic wet etching process can remove Ga2O3 layer and form { 11 10 } p-type GaN stable plane, { 0 1 10 } n-type GaN stable plane on mesa sidewall. This inclined p-type GaN plane of LED structure can provide the higher overlap of incident light beam core and extraction core overlap on mesa sidewall, and total light output power of the treated LED is higher than the standard LED. Consequently, PEC oxidation process and the inclined undercut LED structure are suitable for high efficiency nitride-based LED application.