Optoelectronic studies in nanocrystalline silicon Schottky diodes obtainedby hot-wire CVD

The very usual columnar growth of nanocrystalline silicon leads to electron ic transport anisotropies. Whereas electrical measurements with coplanar el ectrodes only provide information about the electronic transport parallel t o the substrate, it is the transverse transport which determines the collec tion efficiency in thin film solar cells. Hence, Schottky diodes on transpa rent electrodes were obtained by hot-wire CVD in order to perform external quantum efficiency and surface photovoltage studies in sandwich configurati on. These measurements allowed to calculate a transverse collection length, which must correlate with the photovoltaic performance of thin film solar cells. Furthermore, the density of charge trapped at localised states in th e bandgap was estimated from the voltage dependence of the depletion capaci tance of these rectifying contacts. (C) 2001 Elsevier Science B.V. All righ ts reserved.