Strong near-infrared photoluminescence emission of (003)-oriented MgTiO₃ thin films

In this study, ilmenite-MgTiO₃ films were sputtered on p-type Si(111) substrates and the extrinsic effects, such as grain size, crystallinity, and orientation of photoluminescence (PL) properties of the films are discussed. To reduce the effect of oxygen vacancies (act as shallow defects) on PL emissions in the films, oxygen (O₂) was introduced as the sputtering gas and the excitation light source (λ = 532 nm) which has a corresponding energy (hν = 2.33 eV) below the shallow defect states was used. In this study, intense near-infrared (NIR) PL emission centered at 810.1 nm at room temperature can be observed when the MgTiO₃ thin films exhibit the preferred (003)-orientation and accompanied by the presence of hexagon-shaped grains. In this study, the experiment results reveal that the NIR emission intensity of MgTiO₃ films highly depend on crystal orientation and/or grain morphology.