# AlScN Pseudosubstrates for High Indium Content InGaN Alloy Epitaxy

## TL;DR

Researchers developed AlScN pseudosubstrates to improve the growth of high-indium-content InGaN films for efficient red micro-LEDs.

## Contribution

AlScN pseudosubstrates with tunable lattice parameters are introduced as a novel solution for InGaN epitaxy.

## Key findings

- AlScN pseudosubstrates enable phase-pure InGaN films with uniform indium distribution.
- Reduction of compositional pulling effect and improved lattice matching compared to GaN substrates.
- Room-temperature photoluminescence confirms narrow emission at 538 nm from AlScN-supported films.

## Abstract

Nitride-based semiconductors
are vital for efficient optoelectronic
devices in the ultraviolet to green spectral range. However, producing
red-emitting InGaN micro-LEDs is challenging due to lattice mismatch
with traditional GaN substrates. This mismatch causes strain relaxation,
compositional gradients, and defects in high-indium-content InGaN
films. These issues severely limit device efficiency, and the potential
of alternative substrates to address these challenges is not fully
explored. Here, we show that Al1–x
Sc
x
N pseudosubstrates with adjustable
lattice parameters greatly improve lattice matching of InGaN. Using
plasma-assisted molecular beam epitaxy, we grow 120 nm-thick, phase-pure
Al1–x
Sc
x
N layers (0.1 < x
Sc < 0.2). This
enables high-quality deposition of In0.28Ga0.72N layers and a uniform indium distribution compared to growth directly
on GaN. AlScN-supported films exhibit no compositional pulling effect
common for conventional substrates. This uniformity is confirmed by
room-temperature photoluminescence, showing a narrow emission at 538
nm. Our results demonstrate that AlScN pseudosubstrates are promising
for future integrated red micro-LED devices.