Thermal behavior of AlGaN-based deep-UV LEDs
Su-Hui Lin, Ming-Chun Tseng, Ray‐Hua Horng, Shouqiang Lai, Kang-Wei Peng, Meng-Chun Shen, Dong‐Sing Wuu, Shui‐Yang Lien, Hao‐Chung Kuo, Zhong Chen, Tingzhu Wu
Abstract
This study utilized thin p -GaN, indium tin oxide (ITO), and a reflective passivation layer (RPL) to improve the performance of deep ultra-violet light-emitting diodes (DUV-LEDs). RPL reflectors, which comprise HfO 2 /SiO 2 stacks of different thickness to maintain high reflectance, were deposited on the DUV-LEDs with 40 nm-thick p -GaN and 12 nm-thick ITO thin films. Although the thin p -GaN and ITO films affect the operation voltage of DUV-LEDs, the highly reflective RPL structure improved the WPE and light extraction efficiency (LEE) of the DUV-LEDs, yielding the best WPE and LEE of 2.59% and 7.57%, respectively. The junction temperature of DUV-LEDs with thick p -GaN increased linearly with the injection current, while that of DUV-LEDs with thin p -GaN, thin ITO, and RPL was lower than that of the Ref-LED under high injection currents (> 500 mA). This influenced the temperature sensitive coefficients (dV/dT, dLOP/dT, and dWLP/dT). The thermal behavior of DUV-LEDs with p -GaN and ITO layers of different thicknesses with/without the RPL was discussed in detail.