Subthreshold Characteristics and High-Frequency Performance in InAlAs/InGaAs MHEMT with a Liquid Phase Oxidized InAlAs Gate

The oxidation of InAlAs and its application to 0.65 mum InAlAs/InGaAs metal-oxide-semiconductor metamorphic high electron mobility transistors (MOS-MHEMTs) are demonstrated in this study. After the highly selective gate recessing of InGaAs/InAlAs using citric buffer etchant, the gate dielectric is obtained directly by oxidizing the InAlAs layer in a liquid phase solution near room temperature. As compared to its counterpart MHEMT, the studied MOS-MHEMT exhibits a larger gate bias operation, higher breakdown voltage, lower subthreshold current, improved gate leakage current with the effectively suppressed impact ionization effect, and improved RF performance