Low temperature hydrogenated microcrystalline silicon-carbon alloys deposited by RF-PECVD

Two sets of hydrogenated microcrystalline silicon carbon alloys were deposited by standard radio frequency (RF) plasma enhanced chemical vapor deposition at a substrate temperature of 175 °C. The effect of the methane flow rate and of the RF-power were investigated. Samples were deposited from a silane and methane gas mixture, highly diluted in hydrogen. The increase in methane flow rates leads to a decrease of the crystalline volume fraction and an increase in carbon incorporation. On the other hand, decreasing the RF-power shifts the microcrystalline-to-amorphous transition at higher methane flow rates. Moreover, for similar amount of carbon incorporated, the decrease in RF-power leads to materials showing higher crystalline volume fraction and average grains sizes. Both ion bombardment energy and carbon incorporation contributes to the microstructural properties of the deposited alloys.