We have grown GaN epilayers, with a thickness of 1.3 to 1.4 mum, on 100 mm diameter Si(111) substrates. The GaN films were grown by using buffer layers consisting of 3C-SiC and 2H-AlN. The GaN films were flat and smooth without noticeable micro-cracks but had slip lines. The x-ray diffraction and electron diffraction analyses showed that each of the buffer layers and the GaN film were single-crystals. The room temperature PL showed that the FWHM was as low as 35.5 meV, the narrowest for all reported GaN/Si films grown by blanket MOCVD.