A method for fabricating semiconductor devices includes: (a) forming a layered structure that includes a temporary substrate, a plurality of spaced apart sacrificial film regions on the temporary substrate, and a plurality of valley-and-peak areas among the sacrificial film regions; (b) growing laterally and epitaxially an epitaxial film layer over the sacrificial film regions and the valley-and-peak areas, wherein gaps are formed among the epitaxial film layer and the valley-and-peak areas; (c) forming a conductive layer to contact the epitaxial film layer; (d) forming a plurality of grooves to divide the epitaxial film layer and the conductive layer into a plurality of epitaxial structures on the temporary substrate; and (e) removing the temporary substrate and the sacrificial film regions from the epitaxial structures by etching the sacrificial film regions through the gaps and the grooves.