GaN MESFETs on (111) Si substrate grown by MOCVD

A GaN metal-semiconductor field-effect transistor (MESFET) has been gown on (111) Si substrate by metalorganic chemical vapour deposition using Al0.27 Ga0.73N/AlN intermediate layers. The device showed a maximum extrinsic tran sconductance 25mS/mm and a drain-source current 169mA/mm with a complete pi nch-off for the 2.5 mum gate-length. The Al0.27Ga0.73N/AlN intermediate lay ers were effective in obtaining a mirror-like surface morphology and a high -resistive undoped GaN layer beneath a channel layer. The GaN MESFET on Si also exhibited no self-heating effects (drain-source current reduction) und er high-power conditions, which results from the better thermal properties of Si than those of sapphire.