Enhanced Device Characteristics of Mos-Hemts with HfO2/Al2O3 Stacked Dielectrics By Using Sputtering/Ozone Water Oxidation Techniques

Enhanced device characteristics of InGaAs/AlGaAs MOS-HEMTs with HfO₂/Al₂O₃ stacked dielectrics by using separate RF sputtering and ozone water oxidization are investigated in this work. Improved interfacial quality is verified by 1/f spectra and C-V measurement. k values of the stacked HfO₂/Al₂O₃ are extracted to be 21.5/9.2, respectively, and the resulted effective oxide thickness (EOT) is 5.15 nm. Excellent switching characteristics of low substhreshold slope (SS) of 70 mV/dec and high I_DS on-off ratio of up to 6 orders are achieved. The present MOS-HEMT has shown comprehensive improvements in  intrinsic voltage gain (A_V),  high frequencies, minimum noise figure (NF_min), output power (P_out), and power-added efficiency (PAE) performances. Besides, hgh-temperature stability in maximum extrinsic transconductance (g_{m, max}), maximum I_DS (I_{DS, max}), and gate-drain breakdown voltage (BV_GD) characteristics are also obtained. The present MOS-HEMT design is promising for high temperature and power-switching MMIC applications.