Metal±insulator±semiconductor (MIS)-type solar cells have an inherent cost advantage compared to p-n junction solar cells. First-generation MIS±inversion layer (MIS±IL) solar cells, already successfully produced in an industrial pilot line, are restricted to eciencies of 15±16%.
With the second-generation MIS±IL silicon solar cells, based on drastically improved surface passivation by plasma-enhanced chemical vapour-deposited silicon nitride, simple technology can be combined with very high eciencies. The novel inversion layer emitters have the potential to outperform conventional phosphorusdiused emitters of Si solar cells. A 17.1% eciency could already be achieved with the novel point-contacted `truncated pyramid' MIS±IL cell. A new surface-grooved line-contact MIS±IL device presently under development using unconventional processing steps applicable for large-scale fabrication is discussed. By the mechanical grooving technique, contact widths down to 2 mm can be achieved homogeneously over large wafer areas. Bifacial sensitivity is included in most of the MIS-type solar cells.
For a bifacial 98 cm 2 Czochralski (Cz) Si MIS-contacted p-n junction solar cell with a random pyramid surface texture and Al as grid metal, eciencies of 16.5% for front and 13.8% for rear side illumination are reported. A 19.5% eciency has been obtained with a mechanically grooved MIS n p solar cell.
The MIS-type silicon solar cells are able to signi®cantly lower the costs for solar electricity due to the simple technology and the potential for eciencies well above 20%.