White electroluminescence from cross relaxation-free CaSiO3:Tb3+ film on silicon wafer and its concentration dependent white-color tunability

Abstract

A full-color white light source is continuously required for general lighting applications. Herein, the white electroluminescence (EL) from Tb3+-singly doped CaSiO3 (CSO) thin film on a silicon substrate has been reported for the first time. The EL device has a metal-oxide-semiconductor (MOS) structure which consists of two CSO and SiOx oxide layers on silicon wafer. Above the threshold voltage in AC power, it shows a full-color white EL spectrum with two dominant emission groups of ultraviolet-blue and green-red peaks from the f-f intra-transition of Tb3+ ions without the cross-relaxation effect in the four blue peaks which suffers from their severe cross-relaxation quenching in its photoluminescence spectrum. It is attributed to the strong electric field splitting (Stark effect) which prevents the resonance energy transfer due to energy perturbation. With increasing Tb3+ concentrations, the blue bands get more dominant along with increasing the threshold voltage. Furthermore, we demonstrate the EL-voltage transient behavior with a large hysteresis in a positive voltage polarity.