High‐Quality GaN Crystal Grown on Laser Decomposed GaN–Sapphire Substrate and Its Application in Photodetector

Abstract

The lack of high‐quality gallium nitride (GaN) wafers may be a non‐negligible bottleneck restricting the development of GaN‐based devices. Although various processing methods have been used to reduce dislocation density, there is still plenty of room for the reduction of stress in GaN crystal. Herein, laser decomposition is verified as an efficient technique to reduce the interfacial stress in GaN–sapphire and improve the lateral epitaxial growth quality of GaN crystal. The variation of the stress on surface and at a depth of 2 μm by controlling the incident pulse energy is systematically studied and the physical mechanism of laser decomposition process is discussed. As the incident energy increases, the stress is weakened within a certain range. Experimental evidences of the good growth quality are displayed by the investigation of high‐resolution X‐ray diffraction, electron backscattered diffraction, and photoluminescence. Furthermore, high‐quality UV photodetectors based on the as‐obtained GaN are fabricated successfully, which show a strong photocurrent response and excellent stability. This work may pave a way towards improving crystal growth and provides a new insight for tuning interface stress so as to develop desired devices.