Damage-Free Plasma Etching to Enhance Performance of AlGaInP-Based Micro-Light Emitting Diode

We investigated the effect of plasma-etching on the electrical and optical performance of lateral AlGaInP-based red micro-LEDs as a function of etching time, where plasma-etched Ag particles were used as masks. For the sample etched for 12 s, around 33% of the sample surface were randomly etched, whereas for the sample etched for 24 s, nearly 60% were randomly etched with additional nanoscale hillocks. Regardless of etching times, all samples exhibited similar forward voltages of 1.944–1.929 V at
$20~\mu \text{A}$
and reverse leakage currents of
$1\times 10^{-8}$
A at −10 V. The micro-LEDs fabricated with 12 s-etched and 24 s-etched
$p$
-GaP gave 26.2% and 42.3% higher light output powers at
$20~\mu \text{A}$
, respectively, than the one with unetched
$p$
-GaP. The
$S$
parameter decreased with increasing forward current and etching time. The electroluminescence (EL) peak intensities of the micro-LEDs were consistent with their light output performance and included shoulder peaks at 612 nm. Emission images showed that the micro-LEDs with the 24 s-etched
$p$
-GaP revealed the most intense and uniform emission area among the three samples.