UC Santa Barbara

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-oxidesemiconductor

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=x) versus

log frequency curves at positive gate bias and the dependence of the frequency dispersion on the

dielectric thickness.