Light-emitting devices based on erbium-doped TiO_2/p~+-Si heterostructures:Engineering of electroluminescence via aluminum co-doping

摘要

We have recently reported erbium (Er)-related visible and infrared (～1540nm) electroluminescence (EL) from the light-emitting device (LED) based on Er-doped TiO_2 (TiO_2:Er)/p~+-Si heterostructure, triggered by the energy transferred from oxygen-vacancy-related self-trapped excitons (STEs) to Er~(3+) ions in anatase TiO_2. Herein, we further co-dope aluminum (Al) into the TiO_2:Er film, which is also used to form heterostructure with p~+-Si. The LED based on such heterostructure features the Er-related EL with the substantially suppressed visible emissions and the remarkably enhanced ~1540nm emission. The Al co-doping is proved not to substantially affect the amounts of oxygen-vacancy-related STEs and Er~(3+) ions in anatase TiO_2. In this context, the above-mentioned engineering of Er-related EL is tentatively ascribed to the modification of crystal field around the Er~(3+) ions in anatase TiO_2 by the Al co-doping.