“…Capacitance-voltage measurements at a fixed frequency provide a method of determining fixed charge density in the insulator region, interface density, insulator thickness, and impurity density in the semiconductor region. Combined with capacitance measurements versus frequency at fixed biases, these measurements can be used to determine surface potential, standard deviation of surface potential, and interface state density and majority carrier cross section as a function of surface potential [25,26]. For these reasons, automatic C-V plotting instruments have been developed, particularly for the evaluation of impurity density versus distance in Schottky and junction devices, for example, the second harmonic method of Copeland [27]; the mixed frequency technique of Baxandall [28]; and the techniques of Gordon, Stover, and Harp [29];…”