Photocapacitance effect at low temperatures in a unipolar MIS capacitor with a semiconductor electrode doped with two different acceptor impurities

The photocapacitance effect at low temperatures in a unipolar MIS capacitor with a semiconductor electrode doped with two types of acceptor impurities characterized by different ionization energies E-ia (deep-level acceptor) and E-ib (shallow-level acceptor) is examined theoretically. It is shown th at the photocapacitance response of such a capacitor arises in a relatively narrow range of bias voltages. The maximum of the response at a constant b ias depends on the temperature as exp(E-ia/kT ). An infinite increase in th e photocapacitance response is related to the singularity that appears with decreasing temperature in the bias-voltage dependence of the ionized accep tor concentration. The capacitance and photocapacitance characteristics for a structure with a silicon electrode doped with In and B are calculated. ( C) 2001 MAIK "Nauka/Interperiodica".