Mechanism of electroluminescence in the amorphous silicon-based erbium-doped structures

We have studied electroluminescence (EL) in amorphous silicon-based erbium-doped structures at reverse bias in the temperature range 77–300 K. The intensity of electroluminescence at the wavelength of 1.54 μm corresponding to a radiative transition 4I13/2→4I15/2 in the internal 4f-shell of the erbium ion Er3+ is low at 77 K but sharply increases starting from 220 K and exhibits a maximum near the room temperature. Theoretical analysis and comparison with the experiment have shown that the excitation of erbium ions occurs by an Auger process, which involves the capture of conduction electrons by neutral dangling bonds (D0) defects located close to erbium ions. It is demonstrated that the stationary concentration of free electrons in the conduction band is kept by a reverse process being multiphonon tunnel ionization of erbium-induced donors and D−-centers by the applied electric field.