Variation in structure and photoluminescence in SrTiO sub(3) film buffered by SrRuO sub(3)

Blue-light emission at room temperature was observed in SrTiO sub(3) film with SrRuO sub(3) as buffer layer on LaAlO sub(3) substrate. Other SrTiO sub(3) films, such as grown directly on LaAlO sub(3) and GaAs substrate or with DyScO sub(3) as buffer layer on LaAlO sub(3), which all have a single-orientated structure, showed no visible light excitation. A double-orientated structure was characterized in the SrRuO sub(3) buffered SrTiO sub(3) by multiple X-ray diffraction techniques. After post-annealing in nitrogen at 500 degree C for 12 h, the photoluminescence signal increased moderately while the double-orientated structure did not change at all. And still, no visible light excitation was observed in the other single-orientated films after post-annealing. We argued that the structure disorder induced by the SrRuO sub(3) buffer is the basis for the blue-light emission.