PNNL

Abstract

We use in situ and ex situ experiments along with classical and quantum mechanical modeling to investigate the nuances of insulating layer formation in otherwise high-mobility homoepitaxial n-SrTiO3(001) films deposited on undoped SrTiO3(001). Our analysis points to charge immobilization at the buried interface as well as within the surface contamination layer resulting from air exposure as the drivers of electronic dead-layer formation. As Fermi level equilibration occurs at the surface and at the buried interface, charge trapping reduces the sheet carrier density (n2D) and renders the n-STO film insulating if n2D falls below the critical value for the metal-to-insulator transition.