Impact of weak Fermi-level pinning on the correct interpretation of III-V MOS C-V and G-V characteristics

The commonly encountered frequency dispersion and distorted behavior of GaAs and III-V MOS C-V and G-V is clarified by using MOS interface state theory. The relation of the C-V behavior with Fermi-level pinning of III-V MOS is explained. It is shown why it is difficult to quantify the interface state density using the conductance method for III-V MOS. A qualitative distinction of interface state behavior from common frequency dispersion due to series resistance is also put forward and guidelines are given to properly interpret III-V admittance data.