Crystalline Silicon Thin-Film Solar Cells on Silicon Nitride Ceramic Substrates

Abstract

Photovoltaics - the generation of electricity from sunlight - is a technically challenging but environmentally benign technology to generate electricity with a large econnomical potential. However, the major hurdle for its widespread usage is its present high cost. Various thin-film solar cell technologies are investigated to bring down the total cost to an economic value. One of them, the crystalline silicon thin-film (CSiTF) solar cell combines the advantages of conventional wa fer-based silicon solar cells such as high efficiency and non-toxicity with the benefits of thin-film technologies such as serial interconnection and large area deposition. This paper reports for the first time the preparation of CSiTF solar cells on specially developed Si 3 N 4 ceramic substrates. Three different types of Si 3 N 4 recomme wafers were single-sided coated with 10 μm of microcrystalline silicon, which was recrystallized by a zone melting step and subse quently thickened to approx. 30 μm. Optical analysis of the layer surface and cross sections was done to determine the crystallographic properties of the silicon layers, as well as mass spectroscopy to measure the concentration of transition metal impurities. A one-side conducted solar cell process was applied on non-conducting Si 3 N 4 substrates. The best 1 cm 2 cells achieved an efficiency of 8.0% with an excellent fill factor of 74% and an open circuit volonge of 554 mV. The solar cell characterization was complemented by measurements of dark current-voltage characteristics spectrally resolved light beam induced current mapping, and external quantum efficiency.