Performance improvement of blue light micro-light emitting diodes (< 20 μm) by neutral beam etching process

Abstract

In this study, micro-light emitting diodes array (μLEDs) with dimensions of 5 μm and 15 μm chip size were fabricated using Neutral Beam Etching (NBE) processes. Size-dependent issues of μLEDs processed by traditional inductively coupled plasma-reactive ion etching (ICPRIE) were alleviated by NBE technology, which exhibited lower equivalent resistance, turn-on voltage, and Ideality factor as compared with those of μLEDs by ICPRIE. Additionally, higher light output power of μLEDs processed by NBE with both 5 μm and 15 μm resulted in higher EQE 7.6 % and 7.7 % than those of μLEDs processed by ICPRIE. Furthermore, the size effect led to a decrease in EQEmax values of the ICPRIE sample by 0.4 %, but only a 0.1 % decay in NBE. Overall, samples fabricated by the NBE process exhibited superior optoelectronic characteristics. Finally, non-radiative recombination behaviors on the mesa sidewall were verified by cathodoluminescence analysis, showing significant decay in ICPRIE samples but not in NBE samples. These results demonstrated the potential of the NBE process for fabricating small chip sizes blue-light μLEDs required for high-brightness, high-efficiency, and high-resolution μLED displays.

Keywords

• Micro-LED
• Neutral beam etching
• Inductively coupled plasma-reactive ion etching
• Non-radiative recombination