InGaAs metal-semiconductor field-effect transistor with Langmuir-Blodgett deposited gate structure

A high-transconductance n-channel, depletion-mode InGaAs metal-semiconductor field-effect transistor (MESFET) with a Langmuir-Blodgett deposited gate fabricated on organometallic chemical vapor deposition (OMCVD)-grown InGaAs lattice matched to InP is reported. The fabrication process is similar to epitaxial GaAs FET technology and is suitable for making optoelectronic integrated circuits (OEICs) for long-wavelength fiber-optic communications systems. Devices with 1- mu m gate and 6*10/sup 16/ channel doping achieved 162-mS/mm extrinsic transconductance and -1.8-V pinch-off voltage. The effective saturation velocity of electrons in the channel was measured to be between 3.5 and 3.9*10/sup 7/ cm/s. The drain current (I/sub dss/), 300 mA/mm at V/sub ds/=2.5 V, is the highest current capability reported for depletion-mode InGaAs MESFET devices with low pinch-off voltages.<>