Large area shunt defect free GaAs solar cells

Shunt defects have been found to be the type of defect that can degrade and cause failure in GaAs solar cells. Because of their catastrophic effects, it is necessary to ensure that no shunt defects are formed in the solar cell. A technique for fabricating large-area shunt-defect-free GaAs solar cells has been investigated. A Be-doped GaAlAs window layer was grown directly on an n-type GaAs substrate by isothermal liquid-phase epitaxial growth (ILPE). By growing directly on the GaAs substrate and not growing the usual buffer, absorber, collector, and window layer combination, the fabrication is simplified and yields can be large. It was found that Be from the liquid GaAlAs melt diffused into the GaAs to form a complete collector layer. Because the collector is complete, a shunt-defect-free solar cell is produced. The results of the ILPE growth are reported for both 5.1 cm² and 0.12 cm² solar cells. The technique is very versatile and may be used to fabricate larger-area solar cells