MOS Deep depletion C-V measurements using linear ramp voltages

Deep depletion in a metal-oxide-semiconductor system is analogous to reverse bias in a p-n junction, but it is a transient state. Consequently, deep depletion capacitance versus bias measurements are usually made with a bridge and pulsed bias. It will be shown in this paper that this transient capacitance-voltage measurement can be achieved very simply and directly by measuring the MOS current response to a linear ramp voltage under sweep conditions such that both inversion layer response and surface state response are inhibited, typically 10⁴volts/sec. This MOS current response is proportional to the differential capacitance and carries information on the doping density, flat band voltage, and avalanche breakdown, as well as minority carrier generation effects.