Wafer‐Scale Transferrable GaN Enabled by Hexagonal Boron Nitride for Flexible Light‐Emitting Diode

Abstract Epitaxy growth and mechanical transfer of high‐quality III‐nitrides using 2D materials, weakly bonded by van der Waals force, becomes an important technology for semiconductor industry. In this work, wafer‐scale transferrable GaN epilayer with low dislocation density is successfully achieved through AlN/h‐BN composite buffer layer and its application in flexible InGaN‐based light‐emitting diodes (LEDs) is demonstrated. Guided by first‐principles calculations, the nucleation and bonding mechanism of GaN and AlN on h‐BN is presented, and it is confirmed that the adsorption energy of Al atoms on O 2 ‐plasma‐treated h‐BN is over 1 eV larger than that of Ga atoms. It is found that the introduced high‐temperature AlN buffer layer induces sufficient tensile strain during rapid coalescence to compensate the compressive strain generated by the heteromismatch, and a strain‐relaxation model for III‐nitrides on h‐BN is proposed. Eventually, the mechanical exfoliation of single‐crystalline GaN film and LED through weak interaction between multilayer h‐BN is realized. The flexible free‐standing thin‐film LED exhibits ≈66% luminescence enhancement with good reliability compared to that before transfer. This work proposes a new approach for the development of flexible semiconductor devices.