Interface Engineering Enabling Next Generation GaN-on-Diamond Power Devices

Gallium nitride (GaN)-on-diamond technology offers key parameters of high thermal conductivity, high power density, high electrical resistivity and small form factor at both the device and system levels, making GaN-on-diamond power amplifier devices very attractive for high-power radio-frequency (RF) applications, such as commercial base stations, satellite communications and defence applications. Current GaN-on-diamond integration technology involves either a diamond growth process or a diamond bonding process, both of which require precise interface engineering with appropriate interfacial layers. While such interfacial layers are of vital importance to make high-quality GaN-on-diamond integration possible, they also contribute to a large portion of the effective thermal boundary resistance (TBReff) at the interface, which has to be minimized to justify the benefit of GaN-on-diamond technology compared with the mainstream GaN on silicon carbide (SiC) technology. In this paper, we review the ongoing effort to develop interface engineering processes that position GaN-on-diamond as a promising technology for enabling the next generation of power devices.