Single-phase epitaxial Nb doped BiFeO3 (BFNO) films have been grown on diverse oriented-SrTiO3 substrates by pulsed laser deposition. The orientation dependent surface potential distributions arising from combination of the screen and polarization charges on the BFNO surfaces were characterized by Kelvin probe force microscopy combining with corresponding domain structures investigation using piezoresponse force microscopy. The relationship between surface potential and potential barrier was quantitatively analyzed through tuning the substrate orientation. The present study indicates that data stability and storage density can be controlled via engineering the substrate orientations. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4705405]