Thickness determination of thin (∼20 nm) microcrystalline silicon layers

By analyzing the data of thin μc-Si:H layers (∼20 nm) as well as of thicker layers (∼100 nm) and comparing the results to thicknesses measured with X-TEM, we conclude that as long as the density of thin layers is identical to the thicker layers, with the optical method a good approximation of thickness of microcrystalline silicon layers is possible at a layer thickness down to 20 nm.