Gallium nitride GaN thin films were deposited on Si (111) substrates using electrochemical deposition technique at 20 °C. SEM images and EDX results indicated that the growth of GaN films varies with the current density. XRD and Raman analyses showed the presence of hexagonal wurtzite and cubic zinc blende GaN phases with the crystallite size around 18–19 nm. Photoluminescence spectrum showed that the energy gaps of h-GaN/Si (111) and c-GaN/Si (111) were near 3.39 eV and 3.2 eV respectively at 300 K. Raman spectrum indicated the presence of mixed phonon modes of hexagonal and cubic GaN.