Influence of the growth conditions on the LaAlO3/SrTiO3 interface electronic properties

The effects of oxygen pressure during the growth of LaAlO3 on (001) SrTiO3, and of post-deposition annealing were investigated. While little influence on the structure was observed, the transport properties were found to depend on both growth pressure and annealing. For LaAlO3 layer thicknesses between 5 and 10 unit cells and growth pressures between 10(-4) and 10(-2) mbar, the LaAlO3/SrTiO3 interfaces displayed similar metallic behavior with a sharp transition to a superconducting state. At an oxygen pressure of 10(-6) mbar oxygen vacancies were clearly introduced and extended deep into the SrTiO3 crystal. These vacancies could be removed by post-deposition annealing in 0.2 bar of O-2 at similar to 530 degrees C. At a growth pressure of 10(-4) mbar, the electronic properties of samples with ultra-thin LaAlO3 layers (2 to 3 unit cells thick) were found to depend markedly on the post-annealing step. Copyright (C) EPLA, 2010