Multicrystalline silicon research at the Australian National University

Research in the area of multicrystalline silicon (mc-Si) at the ANU has made systematic use of a quasisteady-state photoconductance technique to measure the electronic properties of the material and monitor their evolution through the different stages of different solar cell fabrication processes. This experimental characterisation has been combined with theoretical modelling to gain a better understanding of the material. Emphasis has been placed on studying the different recombination mechanisms that occur in mc-Si, both in the volume and at the surfaces. This investigation has led to significant contributions, including: a) record minority carrier lifetimes for mc-Si b) first-time measurements of the surface recombination velocity of the SiO2 / mc-Si interface, c) a new cross-contamination technique to separately study the degree of metallic contamination in the material, d) evidence of carrier trapping effects in mc-Si. This characterisation and modelling effort has led to the development of advanced device structures with demonstrated high performance and record 657 mV open-circuit voltages. In a rapid progression, the efficiency of mc-Si solar cells made in our laboratory increased from 14% up to 18.6% for 4 cm(2) mc-Si devices.