ZrO₂ and HfO₂ dielectrics on (001) n-InAs with atomic-layer-deposited in situ surface treatment

The electrical properties of ZrO₂ and HfO₂ gate dielectrics on n-InAs were evaluated. Particularly, an in situ surface treatment method including cyclic nitrogen plasma and trimethylaluminum pulses was used to improve the quality of the high-κ oxides. The quality of the InAs-oxide interface was evaluated with a full equivalent circuit model developed for narrow band gap metal-oxide-semiconductor (MOS) capacitors. Capacitance-voltage (C-V) measurements exhibit a total trap density profile with a minimum of 1 × 10¹² cm^-2 eV^-1 and 4 × 10¹² cm^-2 eV^-1 for ZrO₂ and HfO₂, respectively, both of which are comparable to the best values reported for high-κ/III-V devices. Our simulations showed that the measured capacitance is to a large extent affected by the border trap response suggesting a very low density of interface traps. Charge trapping in MOS structures was also investigated using the hysteresis in the C-V measurements. The experimental results demonstrated that the magnitude of the hysteresis increases with increase in accumulation voltage, indicating an increase in the charge trapping response.