Selectively dry-etched n+-GaAs/N-InAlAs/InGaAs HEMTs forLSI

High-speed n-InAlAs/InGaAs HEMT large-scale integrated circuits must have uniform device parameters. A selectively dry-etched n⁺ -GaAs/N-InAlAs/InGaAs HEMT which has a very uniform threshold voltage is discussed. Despite the high dislocation density at the n⁺-GaAs layer, its performance is excellent. For a gate length of 0.92 μm, the maximum transconductance of the HEMT is 390 mS/mm. The measured current-gain cutoff frequency is 23.7 GHz, and the maximum frequency of oscillation is 75.0 GHz. The standard deviation of the threshold voltage across a 2-in wafer is as low as 13 mV