Contact resistivity and sheet resistance

The contact resistance of the front metallization is an important contribution to the total series resistance of screen-printed solar cells. The transfer length method with a suitable test structure is the best method to separate the contact resistance from other series resistance effects. However, the contact resistance may vary considerably over the solar cell so a method to measure it with spatial resolution on the finished solar cell is necessary. The TLM-SCAN creates mappings of the contact resistivity of a solar cell that is cut into stripes with a laser or a dicing saw.

The mapping on the right demonstrates the resolution and repeatabilty as it shows the same stripe measured 14 times.