Your daily dose of photovoltaic technology developments and solar news

• Popular Technical Papers

  • Overview of automation in the photovoltaic industry
  • Understanding moisture ingress and packaging requirements for photovoltaic modules
  • Evaluation of encapsulant materials for PV applications
  • Inline processing of crystalline silicon solar cells: the holy grail for large-scale manufacturing?
  • PV sector outlook: an analyst’s perspective

• Featured Technical Papers

  • Transparent conducting oxide deposition techniques for thin-film photovoltaics
  • Comprehensive and advanced quality assurance measures for optimal yields from PV power plants
  • Surface passivation of silicon solar cells using industrially relevant Al2O3 deposition techniques
  • Influence of a-Si:H deposition temperature on thermal stability of a-Si:H/SiNx:H stacks
  • Integrated loops: a prerequisite for sustainable and environmentally-friendly polysilicon production

The rapidly-growing photovoltaic market has placed a strong demand on manufacturers to decrease solar cell production costs. For thin-film solar cells, this can be achieved by increasing substrate sizes to achieve a better productivity and by adding more advanced layer stack systems to enhance the solar cell’s efficiency. Nearly all required layers of the prominent thin-film-based solar cell types (a-Si/μc-Si, CdTe and CI(G)S) can be deposited by using plasma processes. On the one hand, plasma-enhanced chemical vapor deposition (PECVD) is used for the deposition of a-Si and μc-Si layers. On the other hand, magnetron sputtering is used for coating with transparent conductive oxides as ITO (indium tin oxide) and ZAO (aluminium-doped zinc oxide), metallic back contact layers such as Ti, Al and Mo, or components of the compound semiconductor layers such as Cu and In. Magnetron sputter processes use direct current (DC) or pulsed DC, whereas radio frequency (RF) power is used for PECVD processes. Of utmost importance to get a reliable, high-efficiency solar cell is a good uniformity of the deposited layers and the need for the layer to be defect-free. Defects such as particles and splashes are created inside the plasma when an unwanted local discharge – a so-called arc – occurs. This arc can be eliminated by switching off the power supply. The faster this is done, and the less energy that is delivered into the arc, the smaller and more insignificant the defect creation will be. For this reason, as well as for precise control of electrical power, advanced, fast-reacting arc management is very important to attain high-quality solar cell coatings.

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