All-refractory GaAs FET using amorphous TiWSi/sub x/ source/drain metallization and graded-In/sub x/Ga/sub 1/spl minus/x/As layers

Abstract

We report on the fabrication of an all-refractory GaAs field-effect transistor having non-alloyed source and drain ohmic contacts and a TiW/Au refractory gate metallization. The ohmic contacts consist of amorphous TiWSi/sub x/ metallization and intervening graded InGaAs layers grown by low pressure organometallic vapor phase epitaxy (LPOMVPE). The amorphous TiWSi/sub x/, is formed using alternating layers of TiW(10 /spl Aring/) and Si(1.5 /spl Aring/) deposited by an RF magnetron sputtering technique. The resulting all-refractory FET devices exhibited excellent dc transistor characteristics with measured transconductance of 140 mS/mm. The dc performance of these devices was comparable to conventional devices with AuGe/Ni/Au contacts fabricated using similar material structures. >