Silicon and carbon based alloys were deposited by hot wire chemical vapor deposition (HWCVD). The microstructure and chemical bonding of these films were characterized by field emission scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The electron microscopy revealed various microstructures were observed for a-C:H, a-SiC:H, a-SiN:H, a-CN:H and a-SiCN:H films. The microstructure of SiN:H films showed agglomerate spherical grains while a-C:H films showed more fractal surface with branched microstructure. However, a-SiC:H, a-CN:H and a-SiCN:H indicated uniform but intermediate surface fractal microstructure. A series of a-SiCN:H films were deposited with variation of NH 3 flow rate. The nitrogen incorporation in a-SiCN:H films alter the carbon network from sp 2 to sp 3 bonding The detail chemical bonding of amorphous films was analyzed by curve fitting method.