Enhanced high-temperature performance of GaN light-emitting diodes grown on silicon substrates

TL;DR

This study reveals that GaN LEDs grown on silicon substrates exhibit superior high-temperature performance and less efficiency droop compared to sapphire-based LEDs, due to improved hole transport and cooler junction temperatures.

Contribution

It demonstrates enhanced high-temperature efficiency in GaN-on-Si LEDs and links this to increased hole transport and junction cooling, challenging conventional expectations.

Findings

GaN-on-Si LEDs show less efficiency droop at high temperatures.

GaN-on-Si LEDs have cooler junction temperatures despite similar structures.

Increased hole transport efficiency accounts for improved high-temperature performance.

Abstract

We compare the temperature dependence of optical and electrical characteristics of commercially available GaN light-emitting diodes (LEDs) grown on silicon and sapphire substrates. Contrary to conventional expectations, LEDs grown on silicon substrates, commonly referred to as GaN-on-Si LEDs, show less efficiency droop at higher temperatures even with more threading dislocations. Analysis of the junction temperature reveals that GaN-on-Si LEDs have a cooler junction despite sharing identical epitaxial structures and packaging compared to LEDs grown on sapphire substrates. We also observe a decrease in ideality factor with increase in ambient temperature for GaN-on-Si LEDs, indicating an increase in ideal diode current with temperature. Analysis of the strain and temperature coefficient measurements suggests that there is an increase in hole transport efficiency within the active region for GaN-on-Si LEDs compared to the LEDs grown on sapphire, which accounts for the less temperature-dependent efficiency droop.