AlGaAs/InGaAs High-Electron Mobility Transistors Fabricated Using Silicon Nitride Passivation and Selective-Etching Process

Abstract

AlGaAs/InGaAs high-electron mobility transistors (HEMTs) are grown by molecular beam epitaxy (MBE). The studied HEMTs use two AlAs layers as etch-stop layers in the selective-etch recessed-gate fabrication of the HEMTs. The influence of passivation using silicon nitride on HEMTs is examined. Passivation improves the dc, high-frequency, and power characteristics of AlGaAs/InGaAs HEMTs. The passivated HEMT has a maximum extrinsic transconductance of 207 mS/mm, a unity-current-gain frequency (fT) of 13 GHz, and a maximum oscillation frequency (fmax) of 26 GHz. Furthermore, the variation of dc characteristics of the passivated HEMT with temperature is reduced.