Solar cell contact resistance—A review

An overview of ohmic contacts on solar cells is presented. The fundamentals of metal-semiconductor contacts are reviewed, including the Schottky approach, Fermi level pinning by surface states, and the mechanisms of thermionic emission, thermionic/field emission, and tunneling for current transport. The concept of contact resistance is developed and contact resistance data for several different contact materials on both silicon and gallium arsenide over a range of doping densities are summarized. Finally, the requirements imposed by solar cells on contact resistance are detailed.