We report on the electrical characteristics of HfO 2 and HfO 2 /Al 2 O 3 gate dielectrics deposited on n-In 0.53 Ga 0.47 As by atomic layer deposition, after in-situ hydrogen or nitrogen plasma surface cleaning procedures, respectively. It is shown that alternating cycles of nitrogen plasma and trimethylaluminum prior to growth allow for highly scaled dielectrics with equivalent oxide thicknesses down to 0.6 nm and interface trap densities that are below 2.5 Â 10 12 cm À2 eV À1 near midgap. It is shown that the benefits of the nitrogen plasma surface cleaning procedure are independent of the specific dielectric. V

A recombination-controlled tunneling model is used to explain the strong frequency dispersion seen in the accumulation capacitance and conductance of dielectric/n-In0.53Ga0.47As metal-oxide-semiconductor capacitors. In this model, the parallel conductance is large when, at positive gate biases, the metal Fermi level lines up with a large density of interface states in the In0.53Ga0.47As band gap. It is shown that the model explains in a semi-quantitative manner the experimentally observed capacitor characteristics, including a peak in parallel conductance/frequency (Gp/ω) versus log frequency curves at positive gate bias and the dependence of the frequency dispersion on the dielectric thickness.

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We report on the influence of variations in the process parameters of an in-situ surface cleaning procedure, consisting of alternating cycles of nitrogen plasma and trimethylaluminum dosing, on the interface trap density of highly scaled HfO2 gate dielectrics deposited on n-In0.53Ga0.47As by atomic layer deposition. We discuss the interface chemistry of stacks resulting from the pre-deposition exposure to nitrogen plasma/trimethylaluminum cycles. Measurements of interface trap densities, interface chemistry, and surface morphology show that variations in the cleaning process have a large effect on nucleation and surface coverage, which in turn are crucial for achieving low interface state densities.

ZrO2 dielectrics were grown on n-In0.53Ga0.47As channels by atomic layer deposition, after employing an in-situ cyclic nitrogen plasma/trimethylaluminum surface cleaning procedure. By scaling the ZrO2 thickness, accumulation capacitance densities of 3.5 μF/cm2 at 1 MHz are achieved. The midgap interface trap density is estimated to be in the 1012 cm−2 eV−1 range. Using x-ray photoelectron spectroscopy, it was shown that the interface contained the oxides of In, Ga, and Al, but no As-oxides or As-As bonds within the detection limit. The results allow for insights into the effective passivation of these interfaces.