Efficient heat dissipation in AlGaN/GaN high electron mobility transistors by substrate-transfer technique

We transferred AlGaN/GaN high-electron-mobility transistors (HEMTs) from a sapphire substrate to a copper plate using a hexagonal boron nitride (h-BN) epitaxial lift-off technique. The bonding adhesion between the HEMTs and the copper plate is improved by optimizing Au–Au thermocompression processes and removing the h-BN residual layer after the lift-off. Thermal resistance estimated by Raman thermography is as low as 6 mm∘C/W, which is comparable to that of a HEMT grown on SiC substrate.As a result, the reduction in I_d versus V_ds due to self-heating effect is suppressed to a negligible level. These results indicate that the substrate transfer technique is effective for achieving high-power performance of GaN-based electron devices.