# Thick GaN film stress-induced self-separation

## TL;DR

This paper investigates the cracking issues in thick GaN films on sapphire during cooling and demonstrates a method for wafer-scale self-separation by modifying film thickness and introducing a buffer layer.

## Contribution

It introduces a novel approach to suppress cracking and achieve wafer-scale self-separation of thick GaN films through thickness ratio control and buffer layer use.

## Key findings

- Cracking was suppressed by increasing film-to-substrate thickness ratio.
- An intermediate carbon buffer layer reduced the binding energy.
- Wafer-scale self-separation of thick GaN films was successfully demonstrated.

## Abstract

Cracking of thick GaN films on sapphire substrates during the cooling down after the growth was studied. The cracking was suppressed by increasing the film-to-substrate thickness ratio and by using an intermediate carbon buffer layer, that reduced the binding energy between the GaN film and the substrate. Wafer-scale self-separation of thick GaN films has been demonstrated.