Effects of roughened window layer on the characteristic of AlGaInP light emitting diodes

• Main Authors: Tao-Chi Chang, 張道淇
• Other Authors: 洪瑞華
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/13159937097027575143

碩士 === 國立中興大學 === 精密工程學系所 === 94 === A surface-roughing technique, employed by chemical wet etching, was studied for the light extraction efficiency of the AlGaInP light emitting diodes (LEDs). The roughing technique used in this dissertation had been effectively reduced the total internal reflection in the LED structure. It results in ~ 30% increasing of external quantum efficiency at 20 mA. The detailed electrical and optical properties of the AlGaInP LEDs were investigated. It was found that the LEDs with roughened surface 48 nm to 151 nm present the output efficiency 7% to 31% at 20 mA as compared with LED with flat surface. The forward voltage was controlled under 2.4 V and current leakage was controlled under 0.1 nA, indicating the absence of the degradation in the electrode contacts. Meanwhile, a reliability test was performed. The deviation of the decrease in light intensity and forward voltage was found within 20% after operating at 50 mA after 200 hours. The test shows that the surface-roughing technique has no significant effect on the device reliability.