Surface depletion in doped SrTiO3 thin films

Strong effects of surface depletion have been observed in metallic La-doped SrTiO3 thin films grown on SrTiO3 substrates by pulsed-laser deposition. The depletion layer grows with decreasing temperature due to the large temperature-dependent dielectric response of SrTiO3. When the depletion layer becomes comparable to or exceeds the thickness of the doped film, the Hall mobility shows significant enhancements as more of the electron distribution extends into the undoped substrate, in conceptual analogy to modulation doping in compound semiconductor heterostructures. (C) 2004 American Institute of Physics.