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 × 10¹²cm⁻² eV⁻¹ and 4 × 10¹²cm⁻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.