Inverted GaAs/AIGaAs heterostructures grown by MOCVD have been used to fabricate conventional ion-implanted MESFETs. Two types of GaAs/AIGaAs heterojunctions are studied. One type has a compositionally graded AlGaAs layer which provides a built-in field and corresponding quantum well at the heterointerface. The other type has a constant-composition AlGaAs layer. 0.5 μm gate devices fabricated using the ungraded AlGaAs layer show a maximum extrinsic transconductance Gmof 280 mS/mm and a small Gmvariation over a gate voltage range of 1.5 V. In comparison, devices fabricated using the graded AlGaAs layer exhibit higher transconductance over all the gate voltages and an enhancement of Gmup to 420mS/mm at low gate bias.
- Ion implantation
- Semiconductor devices and materials
- Semiconductor junctions
ASJC Scopus subject areas
- Electrical and Electronic Engineering