The Si overlayers were grown by solid phase epitaxy on the atomically smooth Er2O3 (111) films, which is prepared on the Si (111) substrate in optimum conditions. The twin structure was observed in the spot-like reflective high energy electron diffraction (RHEED) patterns. The rough surface of Si overlayer, as identified by both RHEED results and Atomic force microscopy (AFM) images, indicated a three dimensional growth mode in contrast to the two dimensional growth mode of Er2O3 on the Si (111) substrate. The physical origin of three dimensional grow is given based on the interfacial energy argument.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.