Total Dose Effects on Surface State Density, Carrier Concentration and Mobility in MOS Layers

Measurements are reported in which the induced carrier concentration and Hall mobility of p-channel MOS structures are determined as a function of surface potential by Hall effect measurements at two different temperatures. The ratio of the Hall mobility to conductivity mobility was also determined. The density of interface states within 6 kT of the valence band edge was calculated. The density of these states generally decreased with ionizing radiation dose and the channel carrier mobility was found to decrease with irradiation at low surface potentials. At high surface potentials, channel carrier mobility was relatively insensitive to ionizing radiation. Carrier scattering mechanisms within the conducting channel are discussed.