Defect evaluation in InGaAs field effect transistors with HfO_2 or Al_2O_3 dielectric

摘要

The performance of InGaAs metal oxide semiconductor field effect transistors with Al_2O_3 or HfO_2 as gate oxide is evaluated and compared. The A12O_3 transistors show the lowest subthreshold slope and mid gap D_(it), however, the HfO_2 transistors reach a higher maximum transconductance (g_(max)) due to the higher oxide capacitance. Both high-κ dielectrics show a g_m-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 HfO_2 devices. Scaling the HfO_2 thickness further reduces the g_m-frequency dispersion, possibly due to detrapping to the gate electrode.