A REAL-TIME STUDY OF THE GROWTH OF MICROCRYSTALLINE SILICON ON TRANSPARENT CONDUCTING OXIDE SUBSTRATES

A detailed real time ellipsometry study of the growth of microcrystalline silicon (mu-c-Si) films on transparent conducting oxide (TCO) substrates is presented. Indium tin oxide and ZnO substrates are compared. mu-c-Si films prepared either from a high power (SiH4,H2) plasma or by alternating the SiH4 and H2 plasmas (layer-by-layer technique) are considered. Insights into the mechanisms of the TCO/mu-c-Si interface formation are obtained. A strong chemical reduction of the TCO substrate is observed during the early stage of exposure to the (SiH4,H2) plasma. Then the ellipsometric measurements reveal an induction period of about 1 min before the nucleation of microcrystallites. mu-c-Si films deposited by the layer-by-layer technique display a different behavior, in particular the chemical interaction at the ZnO/mu-Si interface is not observed in this case.