In situ spectroellipsometry study of the nucleation and growth of microcrystalline silicon

A detailed in situ spectroellipsometry analysis of the nucleation and growth of μc-Si films deposited on c-Si substrate is presented. The deposition is analyzed up to a final thickness of 0.43 μm. In order to perform a precise analysis, various real-time trajectories recorded at different photon energies are studied. New insights into the growth mechanisms are obtained. The growth of μc-Si is described as an evolution of a dense material and microstructures. The dense phase consists of microcrystallites embedded in an amorphous tissue. The nucleation-coalescence mechanism of μc-Si is compatible with a columnar microstructural development during the early stage of the growth. Then a multilayer model is used to describe the formation of a surface roughness. The free surface of μc-Si is rough at a 100–200-Å scale. This surface roughness strongly increases as a function of the deposited thickness. The various stages of the growth of μc-Si and a-Si:H are systematically compared. The growth of a-Si:H displays a more uniform behavior.