Defect evaluation in InGaAs field effect transistors with HfO2 or Al2O3 dielectric

Abstract

The performance of InGaAs metal oxide semiconductor field effect transistors with Al2O3 or HfO2 as gate oxide is evaluated and compared. The Al2O3 transistors show the lowest subthreshold slope and mid gap Dit, however, the HfO2 transistors reach a higher maximum transconductance (gmax) due to the higher oxide capacitance. Both high-κ dielectrics show a gm-frequency dispersion due to tunneling into border traps with a negligible activation energy as determined from temperature dependent measurements. The total amount of trapped charge at border traps is lower in the HfO2 devices. Scaling the HfO2 thickness further reduces the gm-frequency dispersion, possibly due to detrapping to the gate electrode.