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 Id versus Vds 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.