Single-layer SrTiO3 film and SiO2/SrTiO3 composite film white electroluminescence performance comparison

Abstract

Single-layer SrTiO3 film and SiO2/SrTiO3 composite film electroluminescence (EL) devices were fabricated on n-Si substrate though vacuum electron vapor deposition (EBVD) technique. The film layers in the device were analyzed using various detection methods to determine their microstructure and composition, and the EL properties of both types of devices were compared. EL experimental results show that both devices can emit white light visible to the naked eye when the forward bias is applied. Moreover luminescence intensity of SiO2/SrTiO3 composite thin film devices is much higher than that of single-layer SrTiO3 thin film devices. The EL spectrum analysis of the device samples shows that there are three luminescence peaks in both types of devices, and they are located in the blue, yellow and red regions. Three emission peaks of single-layer SrTiO3 thin film devices are located at 460 nm (blue region), 580 nm (yellow region) and 685 nm (red region). Three luminescence peaks of SiO2/SrTiO3 composite thin film devices are located at 460 nm (blue region), 585 nm (yellow region) and 716 nm (red region). In composite film devices, SiO2 acts as an electron barrier layer, confining electrons to the SrTiO3 film layer and increasing the chance for the electrons in the SrTiO3 conduction band to participate in the composite luminescence. As a result, the blue peak emission intensity of the SrTiO3 composite film device is significantly enhanced, while the overall white light emission intensity of the composite thin film device is greatly improved. Additionally, the color coordinates of SiO2/SrTiO3 composite film device is closer to those of standard white light according to CIE standards.