In situ characterization of growing hydrogenated amorphous silicon thin films by p-polarized laser light reflection measurement

In situ p-polarized laser light reflection measurement was applied to the determination of optical constants of growing a-Si:H thin films as well as to the detection of surface transient processes in plasma CVD. Turning off the plasma induced a slight but noticeable change in the reflectance. This reflectance change can be well explained by taking into account the surface relaxation process. When a 2 MHz supersonic vibration was applied to the substrate during the plasma CVD of a-Si:H, it was revealed that the refractive index and absorption coefficient of a-Si:H increased as compared with those deposited without the supersonic vibration. The result indicates that the supersonic vibration works to form a densified a-Si:H network, (presumably by improving the surface reaction).