DC AND AC CHARACTERISTICS OF AL0.25GA0.75AS/GAAS QUANTUM-WELL DELTA-DOPED CHANNEL FET GROWN BY LP-MOCVD

Abstract

Al0.25Ga0.75As/GaAs quantum-well delta-doped channel FET's (QWDFET's) have been successfully fabricated by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The FET's with a gate dimension of 1.8-mu-m x 100-mu-m had a maximum extrinsic transconductance of 190 mS/mm and a maximum current density of 425 mA/mm. The devices showed extremely broad transconductance around its peak. The S-parameter measurements indicated that the current gain and power gain cutoff frequencies of the device were 7 and 15 GHz, respectively. The transconductance versus gate voltage profiles showed a plateau region through a range of 1.7 V supporting spatial confinement of the electrons. These values are among the best reported for delta-doped GaAs-based FET's with a similar device geometry.