Multilayer solar cells with bypass diode protection

A method of forming a thin film solar cell including the steps of:

• (a) forming onto a substrate at least three alternatively doped thin layers of semiconductor material to form at least two rectifying p-n junctions, and
• (b) during the forming step, forming at least one p-n junction portion of the solar cell with doping levels of 10.sup.18 atoms/cm.sup.3 or greater in the adjacent p and n type regions forming said portion.

A method of forming a thin film solar cell including the steps of (a) forming onto a substrate a plurality of alternatively doped thin layers of semiconductor material to form at least one rectifying p-n junction, at least one heavily doped portion of one layer of the solar cell having a doping level of greater than 10.sup.18 atoms/cm.sup.3

• (b) forming sequentially at least two sets of grooves in the plurality of layers to expose some or all of the doped layers, at least one of the grooves passing through and exposing the at least one heavily doped portion,
• (c) forming in at least one of the grooves a p-type surface region over the entire surface of the groove or grooves, and
• (d) forming in at least one other of the grooves an n-type surface region over the entire surface of the respective groove or grooves, the surface of the groove or grooves exposing the heavily doped portion being of opposite dopant type to the heavily doped portion and having a doping level, at least in a region adjacent the heavily doped portion, of 10.sup.18 atoms/cm.sup.3 or greater.