This thesis examines the fabrication, performance, and other aspects of the sliver solar cell. Sliver cells are introduced in the context of global warming; while renewable energy is widely expected to be part of the solution, solar generated electricity is currently more expensive than electricity generated via fossil fuel combustion. Sliver technology offers very promising cost reductions via a large reduction in silicon usage. Sliver cells are high efficiency devices: in this thesis a one-sun cell efficiency of greater than 20% is demonstrated.

Sliver solar cells are fabricated from single crystal silicon wafers; they are very long, thin and narrow solar cells, and are perfectly bifacial. A typical sliver cell manufactured in a mature processing facility would be 10 cm long, 1 mm wide and 30 micro-m thick. Many hundreds to thousands of sliver cells can be fabricated from a single wafer, and it is shown in this thesis that the technology can potentially deliver large gains in solar power output per unit of silicon used in comparison to conventional wafer-based solar technologies. When incorporated into cleverly designed modules, sliver cells use over 7 times less silicon per unit area than conventional modules for today’s technology and are expected to use between 10 and 20 times less silicon when further improvements are incorporated.

Concentrator PV systems are an attractive option for further cost reductions in solar photovoltaic electricity generation. Sliver cells have the potential to fill a void in the concentrator PV market by providing inexpensive, high efficiency solar cells suitable for low to mid-range concentration. If teamed with cheaply produced linear concentrator system optics and tracking, they could be capable of generating electricity at lower costs than either conventional flat-plate modules or tracking high concentration systems.

Concentrator sliver cells are modelled in this thesis as 2D devices using numerical modelling methods. At high illumination intensities or for wide cells, the main loss mechanism in sliver cells is series resistance. Modelling reveals that it is preferable to fabricate concentrator sliver cells from low resistivity substrates and to create heavily doped, deep sidewall emitters. Concentrator sliver cells cannot be fabricated as wide as one-sun sliver cells and can operate in the range 2 – 50 suns.

Various aspects of the fabrication of sliver cells are described, and a preferred simplified processing sequence is developed and discussed in detail. Recombination in sliver cells is examined and this reveals the presence of significant non-ideal recombination at the confluence of two competing diffusions: the sidewall phosphorus and sliver edge boron diffusions. Non-ideal recombination can to some degree be controlled via these two diffusions. Special techniques are introduced for measuring sidewall emitter sheet resistance: a significant result is that sidewall doping is typically between 2 and 2.5 times lighter than doping on planar wafers for the same diffusion. New techniques for metallisation of sliver cells are discussed.

The performance of fabricated sliver cells and concentrator sliver cells are demonstrated for cells produced using the processing sequence developed in this thesis. Efficiencies of greater than 20% are reported for sliver cells with SiN ARC and rear lambertian reflectors. Concentrator sliver cells with oxide only ARC and polished surfaces have recorded efficiencies of 18.8% and 18.4% at concentration ratios of about 10 and 40 respectively. Incorporation of textured surfaces and SiN ARC should result in efficiencies higher than 20% for concentration ratios up to 50.