Sidegating effect of GaN MESFETs grown on sapphire substrate

Abstract

A GaN metal semiconductor field effect transistor (MESFET) with 2 µm gate-length and 200 µm gate-width has been fabricated on a sapphire substrate. The electron mobilities for the n-GaN layer were 585 cm2/V·s with a carrier concentration of 1.1 × 1017 cm–3 at 300 K, and 1217 cm2/V·s with 2.4 × 1016 cm–3 at 77 K. A GaN MESFET showed a transconductance of 31 mS/mm and a drain-source current of 288 mA/mm. The sidegating effect was observed when the negative bias was applied to the sidegate electrode.