Simple Low-Temperature GaN/Diamond Bonding Process with an Atomically Thin Intermediate Layer

Abstract

We demonstrated the low-temperature bonding of GaN and diamond substrates using wet chemical treatments. The GaN and diamond surfaces treated with HCl and NH4OH/H2O2 solutions, respectively, could adhere to each other by contact under atmospheric conditions. After annealing at 200 °C, they were bonded with a shear strength of 8.19 MPa. Interfacial observations revealed that the GaN and diamond crystallines were bonded through an ∼3 nm-thick amorphous layer consisting of Ga, O, and sp2-C. The proposed bonding process consists of wet chemical treatment followed by low-temperature annealing under atmospheric conditions. As this simple process enables GaN/diamond integration without adhesive layers, it would contribute to future high-power and high-frequency GaN devices integrated on the diamond heat spreader.