Efficiency improvement by using metal–insulator-semiconductor structure in InGaN/GaN micro-light-emitting diodes
Jian Yin1, David Hwang2, Hossein Zamani Siboni2, Ehsanollah Fathi2, Reza Chaji2, Dayan Ban1()
1. Department of Electrical and Computer Engineering, Waterloo Institute Nanotechnology, University of Waterloo, Waterloo, ON N2L 3G1, Canada 2. Vuereal InC., 440 Philip Street, Unit 100, Waterloo, ON N2L 5R9, Canada
InGaN/GaN micro-light-emitting diodes (micro-LEDs) with a metal–insulator-semiconductor (MIS) structure on the sidewall are proposed to improve efficiency. In this MIS structure, a sidewall electrode is deposited on the insulating layer-coated sidewall of the device mesa between a cathode on the bottom and an anode on the top. Electroluminescence (EL) measurements of fabricated devices with a mesa diameter of 10 µm show that the application of negative biases on the sidewall electrode can increase the device external quantum efficiency (EQE). In contrast, the application of positive biases can decrease the EQE. The band structure analysis reveals that the EQE is impacted because the application of sidewall electric fields manipulates the local surface electron density along the mesa sidewall and thus controls surface Shockley–Read–Hall (SRH) recombination. Two suggested strategies, reducing insulator layer thickness and exploring alternative materials, can be implemented to further improve the EQE of MIS micro-LEDs in future fabrication.
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