Estimation of trap levels in SrTiO3 epitaxial films from measurement of (LaSr)MnO3/SrTiO3/(LaSr)TiO3 p-i-n diode characteristics

Abstract

We have explored electrical trap levels inside ${\mathrm{SrTiO}}_3$ epitaxial films grown by the pulsed laser deposition method from electrical measurements of semiconducting oxide $\mathrm{p-i-n}$ diodes consisting of ${\mathrm{La}}_{\text{0.85}}{\mathrm{Sr}}_{\text{0.15}}{\mathrm{MnO}}_3/{\mathrm{SrTiO}}_3/{\mathrm{La}}_{\text{0.05}}{\mathrm{Sr}}_{\text{0.95}}{\mathrm{TiO}}_3$ trilayers. The prepared $\mathrm{p-i-n}$ diodes exhibited a marked temperature dependence in their current–voltage $\mathrm{(I–V)}$ characteristics. By attributing the temperature dependence of $\mathrm{I–V}$ curves to the space-charge limitation due to the trapped charges inside the i-${\mathrm{SrTiO}}_3$ layer, we estimated crudely the level of the dominant trap in the ${\mathrm{SrTiO}}_3$ layer as ∼0.09 eV. The trap density was also estimated from the curve-fitting technique. At this moment, the trap densities were ${10}^{16}$ and ${10}^{18}{\mathrm{/cm}}^3$ when ${\mathrm{SrTiO}}_3$ layers were grown at 650 and 630 °C, respectively.