Epitaxial integration of (0001) BiFe O3 with (0001) GaN

Epitaxial growth of (0001)-oriented BiFe O3 thin films on the (0001) surface of GaN has been realized using intervening epitaxial (111) SrTi O3 (100) Ti O2 buffer layers. The epitaxial BiFe O3 thin films have two in-plane orientations: [11 2- 0] BiFe O3 ∥ [11 2- 0] GaN plus a twin variant related by a 180° in-plane rotation. BiFe O3 shows an out-of-plane remanent polarization of ∼90 μC cm2, which is comparable to the remanent polarization of BiFe O3 prepared on (111) SrTi O3 single crystal substrates. The orientation of BiFe O3 realized on GaN provides the maximal out-of-plane polarization of BiFe O3, which is equivalent to a surface charge of 5× 1014 electrons cm2. © 2007 American Institute of Physics.