The impacts of sidewall passivation via atomic layer deposition on GaN-based flip-chip blue mini-LEDs
Shouqiang Lai, Wansheng Lin, Jinlan Chen, Tingwei Lu, Shibiao Liu, Yi Lin, Yijun Lü, Yue Lin, Zhong Chen, Hao‐Chung Kuo, Weijie Guo, Tingzhu Wu
Abstract
Abstract In order to investigate the photoelectric characteristics of 80 × 120 µ m 2 mini-light-emitting-diodes (mini-LEDs) with sidewall passivation by atomic layer deposition (ALD), this paper uses the techniques of spectrometer-based spectroradiometer and microscopic hyperspectral imaging ( µ -HSI). The temperature-dependent electroluminescence is measured using a spectrometer-based spectroradiometer. By analyzing the rising parts of external quantum efficiency at room temperature with a two-level model, the difference of physical mechanisms between mini-LEDs with ALD and without ALD are determined. In addition, the thermal quenching indicates that the ALD sidewall passivation can enhance the temperature stability of the mini-LEDs. The ALD sidewall passivation also enhances the light extraction efficiency according to the theoretical calculation of transmittance. Moreover, the µ -HSI technique is used to evaluate different local areas of mini-LEDs. The obtained results reveal the optimization on lateral distribution of current density within the chip after sidewall passivation.