Frequency dispersion in III-V metal-oxide-semiconductor capacitors

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 (G(p)/omega) versus log frequency curves at positive gate bias and the dependence of the frequency dispersion on the dielectric thickness. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4724330]