Interfaces between (110) and (111)SrTiO3 (STO) single crystalline substrates and amorphous oxide layers, LaAlO3 (a-LAO), Y:ZrO2 (a-YSZ), and SrTiO3 (a-STO) become conducting above a critical thickness t(c). Here we show that t(c), for a-LAO does not depend on the substrate orientation, i.e. t(c), (a-LAO/(110)STO) approximate to t(c)(a-LAO/(111)STO) interfaces, whereas it strongly depends on the composition of the amorphous oxide: t(c)(a-LAO/(110)STO) < t(c)(a-YSZ/(110)STO) < t(c)(a-STO/(110)STO). It is concluded that the formation of oxygen vacancies in amorphous-type interfaces is mainly determined by the oxygen affinity of the deposited metal ions, rather than orientation-dependent enthalpy vacancy formation and diffusion. Scanning transmission microscopy characterization of amorphous and crystalline LAO/STO(110) interfaces shows much higher amount of oxygen vacancies in the former, providing experimental evidence of the distinct mechanism of conduction in these interfaces. (C) 2015 Elsevier B.V. All rights reserved.