Silicon wafer-based technology

Due to the large economical and technological potential of silicon ribbons, their application in solar wafer production will be a major milestone in PV cost reduction. Thus, it is very likely that silicon wafer based PV module manufacturing will maintain the cost advantage over other upcoming technologies and, therefore, the role as the major PV technology. 

Wafer-based crystalline silicon has been the dominant technology since the birth of photovoltaics. It is abundant, reliable and scientifically well understood, as it has enjoyed the knowledge and technology originally developed for the microelectronics... 

Franz et al. [93] developed a palladium membrane micro reactor for hydrogen separation based on MEMS technology, which incorporated integrated devices for heating and temperature measurement. The reactor consisted of two channels separated by the membrane, which was composed of three layers. Two of them, which were made of silicon nitride introduced by low-pressure chemical vapor deposition (0.3 pm thick) and silicon oxide by temperature treatment (0.2 pm thick), served as perforated supports for the palladium membrane. Both layers were deposited on a silicon wafer and subsequently removed from one side completely... 

Current tendencies for multi-crystalline wafer based solar cells are heading towards thinner and larger wafers. Ribbon silicon based wafer technologies have to deal with these developments in the future to maintain their cost effectiveness. As thin EFG and RGS wafers have already been produced on a laboratory scale with thicknesses of <200 fim, their industrial application remains a topic for ongoing research. 

An additional advantage of the integrated circuit technology is the ability to integrate the various components, such as the transducer, reactor, valve, pump etc., within the electronic system, forming refined flow-analysis systems on silicon wafers. Several approaches, such as electrostatic, electromagnetic, piezoelectric, thermopneumatic and thermoelectric can be employed for force transduction in the microvalves, these are also applicable to micropumps. Based on these approaches, two versions of micropumps have been developed. These are connected in parallel the first pump (dual pump) is activated with periodic two-phase voltage, while the second pump (the buffer pump) is driven by two piezoelectric actuators. Microsensors of two kinds are described below a thermopile based- and a thermistor based microbiosensor. 

Fig. 1 Buried contact solar cell structure, an important wafer-based commercial silicon cell technology. Features include surface texturing for light trapping, diffusions front and rear and the front current grid buried in laser grooves. (Courtesy of UNSW Centre for Photovoltaic Engineering Image Library.)...

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