Mechanical transfer of GaN-based devices using layered boron nitride as a release layer

Nitride semiconductors are the preferential choice in various device applications such as optoelectronics and high-power electronics. These gallium nitride (GaN)-based device structures can be grown on sapphire, silicon carbide, and silicon substrates, but not on large, flexible, and affordable substrates such as polycrystalline or amorphous substrates. This article reports our research results that demonstrate that hexagonal boron nitride (h-BN) can form a release layer that enables the mechanical transfer of GaNbased device structures onto foreign substrates. Aluminium (Al) GaN/GaN hetero-structures and indium (In)GaN/GaN multiple-quantum-well (MQW) structures grown on h-BN-buffered sapphire substrates, ranging in area from 25 mm² to 4 cm², were mechanically released from the host substrates and successfully transferred onto other substrates. The electroluminescence intensities from the transferred light-emitting diode (LED) were comparable to or higher than those from a conventional LED on a lowtemperature AlN buffer layer, indicating that the MQW preserved its original quality after the transfer.