The effect of dry etching condition on the performance of blue micro light-emitting diodes with reduced quantum confined Stark effect epitaxial layer

Abstract

As the size of micro light-emitting diodes (mu LEDs) decreases, mu LEDs encounter etching damage especially at the sidewalls that critically affects their properties. In this study, we investigated the influence of etching bias power (P-bias) on the performance of mu LEDs and found that the current-voltage and light output-current characteristics of mu LEDs were enhanced when P-bias was reduced. It was shown that at low P-bias, the chemical reaction between etching gas and gallium nitride, rather than ion sputtering, dominated the etching process, leading to low plasma damage and rough surface morphology. Additionally, to understand the etching-induced surface roughening behaviors, various substrates with different threading dislocation densities were treated at low P-bias. It was found that for the sample (with p-contact size of 10 x 10 mu m(2)), the efficiency droop was approximately 20%, although the current reached 10 mA due most probably to the suppressed polarization effect in the quantum well. It was further observed that the external quantum efficiency (EQE) was dependent on P-bias, where the lowest P-bias yielded the highest maximum EQE, indicating that the plasma damage was mitigated by reducing P-bias. Optimization of dry etching and polarization-suppression conditions could pave the way for realizing high-performance and brightness mu LEDs for next-generation displays.& nbsp;& nbsp;Published under an exclusive license by AIP Publishing.