Gallium nitride (GaN) epitaxial thin films were deposited on Si substrates by a modified hydride vapor phase epitaxy (MHVPE) technique utilizing the GaN seed-layer formed from liquid source precursor. Tris N,N-dimethyldithiocarbamato gallium(III) (Ga(mDTC)3) powder was dissolved in chloroform (CHCl3) to prepare the liquid source precursor for seed-layer formation. The developed method was found to be suitable for the epitaxial growth of GaN on Si in spite of the large mismatch in lattice constants and thermal expansion coefficients, resulting in device-quality epitaxial films with fairly smooth surface morphology. The epitaxial GaN films obtained in this study had a hexagonal structure with (0002) preferred orientation with the FWHM value of 428.6 arcsec of the (0002) GaN XRD peak. Photoluminescence spectra of GaN films exhibited a strong and sharp peak at 3.41 eV with the FWHM value of 107meV.