Electrical characterization of native-oxide InAlP/GaAs metal-oxide-semiconductor heterostructures using impedance spectroscopy

InAIP native oxide/GaAs metal-oxide-semiconductor (MOS) capacitors have been characterized using bias- and temperature-dependent swept-frequency impedance spectroscopy. An equivalent circuit model has been developed for these MOS capacitors that accurately fits the measured impedance over the full frequency range from 40 Hz to 10 MHz. From the bias dependence of the circuit model parameters, the distribution in energy of the interface states was found to be consistent with an exponential distribution, with a total interface state density of 8x10(11) cm(-2) and an average activation energy of 0.34 eV below the conduction band edge. The temperature dependence of the impedance spectra was also examined, and an activation energy of 0.44 eV from the conduction band edge was determined, in good agreement with the bias-dependent impedance measurements. (C) 2004 American Institute of Physics.