Tunneling and impact ionization in thin-film ZnS:Mn-based electroluminescent structures

The errors in determining the depth of the surface-state levels of the insulator-phosphor cathode interface, the width of the potential barrier, and the probability of electron tunneling from the surface states are analyzed using the numerical simulation of experimental time dependences of the current flowing across the phosphor layer. The time dependences of the above parameters for the complete cycle of operation of electroluminescent emitters are obtained, and the effect of the frequency and amplitude of excitation voltage pulses as well as illumination of emitters in the blue spectral region during the interval between the pulses on these dependences is revealed. The time dependences of the multiplication factor and the number of ionization events per electron in the impact ionization region are determined. The largest value of the impact ionization coefficient is estimated to be ≥2.6 × 104 cm−1.