Similarities and differences in the field-induced doping effect of n-type and of intrinsic a-Si : H

Field-induced doping was studied in doped and undoped (intrinsic) a-Si:H samples. It was found that field-induced doping occurs in n-type and intrinsic materials. Capacitance and current measurements on doped and undoped Schottky-diode samples show changes in the capacitance and conductivity after heat treatments at 400 K while keeping the specimen under high electric field. These changes depend on the field direction and can be reversed by a new heat treatment with a zero bias. Field-induced doping effects are attributed mainly to changes in the density of shallow states in n-type materials but in the intrinsic material it is mainly due to increases in the number of deep states.