A full-band Monte Carlo simulation of the high-field electron transport in the ZnS phosphor layer of an alternating-current thin-film electroluminescent device is performed. The simulation includes a nonlocal empirical pseudopotential band structure for ZnS and the relevant scattering mechanisms for electrons in the first four conduction bands, including band-to-band impact ionization and impact excitation of luminescent centers. The steady-state electron energy distribution in the ZnS layer is computed for phosphor fields from 1 to 2 MV/cm. The simulation reveals a substantial fraction of electrons with energies in excess of the impact excitation threshold. The computed impact excitation yield for carriers transiting the phosphor layer exhibits an approximately linear increase with increasing phosphor field above threshold. The onset of impact excitation coincides with the onset of band-to-band impact ionization of electron-hole pairs which prevents electron runaway at high electric fields.
High-field transport and electroluminescence in ZnS phosphor layers
Manfred Dür, Stephen M. Goodnick, Shankar S. Pennathur, John F. Wager, Martin Reigrotzki, Ronald Redmer; High-field transport and electroluminescence in ZnS phosphor layers. J. Appl. Phys. 15 March 1998; 83 (6): 3176–3185. https://doi.org/10.1063/1.367085
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