Dispersive-Transport-Controlled Luminescence in Hydrogenated Amorphous Silicon

Significant differences in the features of the electroluminescence (EL) and photoluminescence (PL) in amorphous silicon p-i-n structures have been observed. At low temperatures the EL peak energy is .apprx.0.2 eV lower than that of the PL, shifts to lower energies with temperature only weakly relative to PL, and also shifts to higher energy with increasing electric field. The EL efficiency showsa maximum at the temperature at which the carrier transport mechanism changes. The long-standing puzzling differences between EL and PL are described not as experimental artifact but as a direct result of the physics governing trapping and transport in amorphous materials.