Integration of Diamond with GaN for Thermal Management in High Power Applications

Heat dissipation is an important consideration for electronic devices used in high power applications. Diamond is considered to be a suitable material to promote heat transfer away from the active regions of devices, and recently, several techniques have been developed to integrate diamond with GaN layers to achieve effective heat dissipation. Since the deposition of diamond onto GaN requires the inclusion of interfacial layers, the stability of these layers plays a large role in their effectiveness to protect the GaN substrate. In this work, samples with SiN or no interfacial layer have been analyzed before and after diamond deposition to study the influence of the by-products of diamond chemical vapor deposition on the interfacial layer. Characterization of the interfacial layer was performed using transmission electron microscopy and x-ray reflectivity. For example, a similar to 6.3 nm SiN layer deposited on a GaN structure prior to diamond deposition was reduced to 2 nm after deposition. The layer remained continuous and offered protection to the underlying GaN substrate. The interface of samples without an interfacial layer were much rougher than those with interfacial layers. In addition, the controlled removal of the dielectric layer at the start of the diamond deposition reduces the contribution of these low thermal conductivity layers to thermal resistance.