The deposition and fundamental properties of a-Si1-xCx:H thin films made using a butane gas source, and of microcrystalline films including pc-Si:H and mu c-3C-SiC:H are reviewed from the viewpoint of hetero-junction formation. The durability of TiO2 thin films upon atomic hydrogen exposure is also reviewed for suppressing the deoxidation of transparent electrodes accompanied by the use of a new microcrystalline silicon carbon alloy for a window layer. The future direction for the development of hetero-junction Si thin film solar cells by hot-wire CVD is discussed. (c) 2005 Elsevier B.V. All rights reserved.