In0.53Ga0.47As FET's with insulator-assisted Schottky gates

Schottky-gate FET's have been fabricated on n-type In
0.53
Ga
0.47
As using a thin interfacial silicon nitride layer between the metal and the epitaxial layer to reduce the gate leakage current. In
0.53
Ga
0.47
As was grown by molecular beam epitaxy on semi-insulating InP substrates and silicon nitride was grown by plasma-enhanced chemical vapor deposition. Devices with 1.2µm gate length and net donor doping in the mid 10
¹⁶
cm
^-3
range show dc transconductance of up to 130mS/mm. Both depletion and enhancement mode operation were observed. The effective saturation velocity of electrons in the channel is deduced to be 2.0 ± 0.5 × 10
⁷
cm/sec, a value 60 to 70% higher than that in GaAs MESFET's. The insulator-assisted gate technology has many advantages in fabrication flexibility and control compared with other approaches to realizing high-speed microwave and logic in FET's in In
0.53
Ga
0.47
As.