Open AccessEnhancing reliability of InGaN/GaN light-emitting diodes by controlling the etching profile of the current blocking layer
Author(s) -
ShuiHsiang Su,
Chun-Lung Tseng,
C.F. Shen,
I-Jou Hsieh,
Yen-Sheng Lin
Publication year - 2020
Publication title -
materials research express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 35
ISSN - 2053-1591
DOI - 10.1088/2053-1591/ab7c84
Subject(s) - light emitting diode , optoelectronics , materials science , etching (microfabrication) , diode , layer (electronics) , chemical vapor deposition , plasma enhanced chemical vapor deposition , reliability (semiconductor) , degradation (telecommunications) , power (physics) , nanotechnology , electronic engineering , physics , quantum mechanics , engineering
SiO 2 was used as the current blocking layer (CBL) during fabricating the InGaN/GaN-based light-emitting diodes (LEDs). The SiO 2 film was prepared by plasma enhanced chemical vapor deposition (PECVD) at a lower temperature (LT) of 180 °C and a higher temperature (HT) of 280 °C for characterizing the reliability of LEDs. The degradation of output power in LT-CBL LED is as high as 6.8% during 1000 h in the high-temperature and humidity (85 °C/85 RH) condition. Experimental results demonstrate the low temperature grown CBL forms a larger side-wall angle via wet etching. The thinner side-wall ITO film cracks and the current spreading effect is suppressed, causing drastic power degradation. On the contrary, the HT-CBL SiO 2 demonstrates optimal step coverage of ITO film for current spreading and then the HT-CBL LEDs slightly degrade as low as 5% in the accelerated reliability test. A dense quality of HT-CBL SiO 2 as well as a good CBL decreased parasitic optical absorption in the p -pad electrode and p -finger. Besides, the HT-CBL SiO 2 showed a small side-wall angle of 40˚ which increased the step coverage and current spreading of ITO. An approach is conducted to confirm the side-wall profile of CBL for each process.