About manifestation of field effect in photoinduced electron emission of Al2O3

By the methods of photoinduced electron emission (PSEE) the processes in anion sublattice of dosimetric corundum crystal in presence of internal electric field of low intensity were studied. PSEE excited spectra were calculated in vacuum ∼10-4 Pa at room temperature. Kinetics of charges accumulation under crystals irradiation by quanta with energy 6.2 eV in electric field have been controlled by damping curves of PSEE. In initial state of corundum sample the maximum at 205 nm have been observed in PSEE spectrum, that is corresponds to F-centers optical absorption field. After crystal irradiation by light in F-centers absorption band during ∼5 min in photoelectrons take-off regime the maximum in excitation spectrum is registered in F-centers absorption band at 230 nm. After 30 min of sample keeping in darkness the relaxation of PSEE spectrum to initial one have been observed. Excitation of samples by radiation wave with length of 205 nm without current take-off does not conduct to change of PSEE excitation spectrum. It was concluded that FSEE allows to observe the defects overcharge processes in aluminium oxide surface layers