Amorphous silicon dioxide thick films were prepared on glass and silicon substrates by plasma-enhanced chemical vapor deposition using hexamethyldisilazane H-2, and CO2, where the H-2 acted as a reactant and carrier gas. These films were studied by choosing different substrate temperatures, radio frequency (rf) discharge power, and flow rates of H-2 and CO2. A variation in the heat of adsorption with rf power was identified. The films were characterized by electron spectroscopy for chemical analysis and scanning electron microscopy. The growth rate increased with rf power, but decreased with increasing substrate temperature. An adsorption-controlled reaction was identified in this system with a varying heat of adsorption depending on the rf power. Hardness changed with experimental parameters and varied in the range of 10-16 GPa. Scratch tests showed a brittle fracture of the thick films. The internal stress of the thick films was determined for different deposition parameters. Refractive indices of the thick films also were measured and varied in the range of 1.33-1.61.