Field induced emission mechanism in ITO/glass/ITO system

Abstract

Results of the field induced electron emission into the vacuum from glass-ITO film system have been presented. Thin Sn-doped In2O3and Sb-doped SnO2layers have been deposited onto both surfaces of silica glass by using the constant–current ion sputtering method. The final structure of an emitter consists of a thin ITO film as electron emitting layer, the glass as dielectric and about 103nm ITO as the field electrode. When negative voltage is applied to the field electrode, it creates an internal field, which favors electron emission into vacuum. The studies have been carried out in the vacuum of 10-7hPa. The mean electric field in the dielectric has been estimated to be 106V/m and E ≥ 107V/m in the ITO layer. The investigation showed that in the glass-ITO systems field induced electron emission and photoemission occur and that their yields depend on field intensity of the emitter, the ITO films thickness and the composition of the film. Electron emission occurs when polarizing voltage is applied and/or the film is UV illuminated. The paper presents a phenomenological model which takes into account some possible mechanisms of field induced emission into the vacuum. The model is based on the assumption that regions of enhanced and depleted charge carriers appear both in the semiconductor layer (ITO) and in the glass-ITO interface. The field and UV light induced electron emission phenomena occur in the studied emitters of ITO layers for the field intensity of the range from 1 to 10 MV/m.