A detailed real time ellipsometry study of the growth of microcrystalline silicon (&mgr;c‐Si) films on transparent conducting oxide (TCO) substrates is presented. Indium tin oxide and ZnO substrates are compared. &mgr;c‐Si films prepared either from a high power (SiH4,H2) plasma or by alternating the SiH4and H2plasmas (layer‐by‐layer technique) are considered. Insights into the mechanisms of the TCO/&mgr;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. &mgr;c‐Si films deposited by the layer‐by‐layer technique display a different behavior, in particular the chemical interaction at the ZnO/&mgr;‐Si interface is not observed in this case.