Microcrystalline Silicon Thin-Film Solar Cells Prepared at Low Temperature

Numerical Simulation of Microcrystalline Silicon Growth on Structured Substrate

The growth of thin-film silicon close to the amorphous/microcrystalline transition is qualitatively described by a 3D - discrete dynamical growth model on a cubic lattice. The result of this simulation is a representation of the microstructure of the layer as a function of time, i.e. computer-generated animations of growing microcrystalline silicon layers. It permits to follow the evolution of the nucleation and of the growth of the crystalline phase, the surface roughness, the average crystalline volume fraction and the void volume fraction. In these computer simulations, the effects of the substrate surface morphology and of the distribution of particles incidence angle have been studied.

Comparison between simulated normal and isotropic incidence on structured substrates indicates that, under microcrystalline growth conditions, shadowing effects lead to the occurrence of cracks in the simulated microstructure. These effects are also evidenced experimentally in the case of μc-Si:H silicon layers deposited by very high frequency plasma-enhanced chemical vapour deposition (VHF-PECVD) on periodic and random nanostructured substrates.