Cadmium telluride thin-film solar cells are now commercially available and are being widely deployed in terrestrial,
photovoltaic, power plants. However, the price of electricity from such sources would be more competitive with
conventionally generated electricity if the cell efficiency could be improved without compromising the generally low-cost
nature of the fabrication process. Recognizing that laboratory cells appear to have reached an efficiency limit of
about 16.5%, we propose to improve on this by adding a thin-film germanium cell in a monolithic, tandem arrangement.
Here we report on simulations of the photovoltaic performance of this structure, and we indicate that an efficiency
improvement in excess of 20% may be attainable.
A simple, non-equilibrium model is used to evaluate the likely DC performance of carbon nanotube field-effect transistors. It is shown that, by appropriate work function engineering of the source, drain and gate contacts to the device, the following desirable properties should be realizable: a sub-threshold slope close to the thermionic
limit; a conductance close to the interfacial limit; an ON/OFF ratio of around 103; ON current and transconductance close to the low-quantum-capacitance limit.