SIDEGATING EFFECT OF GAN MESFETS GROWN ON SAPPHIRE SUBSTRATE

A GaN metal semiconductor field effect transistor (MESFET) with 2 mu m gate-length and 200 mu m gate-width has been fabricated on a sapphire substrate. The electron mobilities for the n-GaN layer were 585 cm(2) /V.s with a carrier concentration of 1.1 x 10(17) cm(-3) 300 K, and 12 17 cm(2)/V.s with 2.4 x 10(16) cm(-3) at 77 K. A GaN MESFET showed a t ransconductance of 31 mS/mm and a drain-source current of 288 mA/mm. T he sidegating effect was observed when the negative bias was applied t o the sidegate electrode.