GaN-HEMT Epilayers on Diamond Substrates: Recent Progress

Gallium-nitride high-electron-mobility transistors fabricated on diamond substrates are highly desired for use in high-power amplifiers for X- Band radar systems and commercial cellular-base stations. Diamond substrates have high thermal conductivity which enables highly efficient removal of heat from the active device regions. This paper describes our progress towards manufacturability of commercial-grade gallium- nitride-transistor epilayers on diamond substrates. We report on the fabrication of the thickest (100 µm) and largest (4") GaN-on- Diamond composite wafers to date and show selected material characterization results.