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 R. The int ensity of electroluminescence at the wavelength of 1.54 mum corresponding t o a radiative transition I-4(13/2)--> I-4(15/2) 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 a nd comparison with the experiment have shown that the excitation of erbium ions occurs by an Auger process, which involves the capture of conduction e lectrons by neutral dangling bonds (D-0) defects located close to erbium io ns. It is demonstrated that the stationary concentration of free electrons in the conduction band is kept by a reverse process bring multiphonon tunne l ionization of erbium-induced donors and D--centers by the applied electri c field. (C) 2001 Elsevier Science B.V. All rights reserved.