Green Semipolar ($11\overline{2}2$) InGaN Micro-Light-Emitting-Diodes on ($11\overline{2}2$) GaN/Sapphire Template

In this work, we fabricated five different sizes of 520 nm semipolar micro-light-emitting-diodes (
$\mu \text{LEDs}$
), ranging from 100×100 to
$20\times 20\mu \mathrm{m}^{2}$
, on (11–22) GaN/sapphire template. Based upon the results from atom probe tomography (APT), no InGaN cluster was observed in the active region. For the current-voltage characteristics, the voltages were 3.2 V and 3.0 V at 60 A/cm
²
for the 100×100 and
$20\times 20\ \mu \mathrm{m}^{2}\ \mu \text{LEDs}$
, respectively. In terms of the optical aspect, the
$20\times 20\mu \mathrm{m}^{2}\mu \text{LED}$
demonstrated a trivial blue-shift of 9 nm as the inject current density increases from 5 A/cm
²
to 100 A/cm
²
. Moreover, for the external quantum efficiency (EQE) performances,
$\mu \text{LEDs}$
in all sizes yielded 6-8% efficiency droop between the peak EQE current density and at 100 A/cm
²
, and the peak EQE was 2% for all
$\mu \text{LED}$
sizes. Although further improvements on growth and materials are required for better
$\mu \text{LED}$
performances, this demonstration revealed the feasibility to produce long-wavelength semipolar InGaN
$\mu \text{LEDs}$
with high efficiency on large-area sapphire substrates.