Monodisperse sub-micrometer-sized silica balls are employed as an intermediate layer for the heteroepitaxial growth of GaN thin films on Si(111) substrates (see figure). The structural and optical characteristics of the films are shown to be improved compared to conventional techniques, as the maskless overgrowth technique employed simplifies the growth process. This method could be exploited to grow other heteroepitaxial films on substrates with large lattice constants and thermal expansion coefficient mismatches.