Effects of ITO Contact Sizes on Performance of Blue Light MicroLEDs

Yu-Hsuan Hsu; Yu-Yun Lo; Yi-Hsin Lin; Hsiao-Wen Zan; Ray-Hua Horng

doi:10.1186/s11671-022-03754-9

Effects of ITO Contact Sizes on Performance of Blue Light MicroLEDs

Nanoscale Res Lett. 2022 Nov 28;17(1):113. doi: 10.1186/s11671-022-03754-9.

Authors

Yu-Hsuan Hsu¹, Yu-Yun Lo¹, Yi-Hsin Lin¹, Hsiao-Wen Zan¹, Ray-Hua Horng²

Affiliations

¹ Department of Photonics, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC.
² Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC. rayhua@nycu.edu.tw.

Abstract

In this study, the effect of ITO contact ratio for blue light micro-light-emitting diode (µLED) with dimensions 40 μm × 40 μm was assessed. The contact ratio from 0.2 to 0.8 was designed for the ratio of electrode area to light-emitting area. As the contact ratio increased from 0.2 to 0.8, the turn-on voltage of µLED decreased. It could be due to the short lateral diffusion length in multiple quantum wells (MQW) and lower parallel resistance for the µLED with a large contact ratio. The leakage currents of single µLED were below 5.1 × 10^-9 A, no matter the contact ratio. It means that the contact ratio does not affect the leakage current as measured on single chip. Moreover, µLED array with a 0.8 contact ratio presented the highest output power than other samples (5.25 mW as the current density of 1875 A/cm²). It could attribute to the MQWs usage, the metal contact reflective behavior and less current crowding, which generated more carriers and extracted more lighting from the µLED. The simulation data using SpeCLED software agreed well with these experiments, and µLED with a 0.8 contact ratio showed the best optoelectronic properties.

Keywords: Blue light; Contact ratio; Current crowding; Micro-LED.