Interface screening effects on semiconducting thin films

We report on our study on the influence of interface screening on the properties of semiconducting thin films utilizing EuO as a model system. EuO films of various thicknesses were grown by molecular beam epitaxy and interfaced half with metallic Mg and half with insulating MgO. The magnetic characterization clearly shows that the lowering of the EuO Curie temperature for ultra-thin films is much delayed and less significant for the EuO part covered with the metal compared to the EuO part interfaced with the insulator. Our results strongly suggest that the proximity of a highly polarizable material can counteract finite size effects in semiconducting films, and point out the importance of considering the dielectric properties of each layer when designing a nanoscale heterostructure device.