Wide band gap Gallium Phosphide solar cells for multi-junction solar cell system

Gallium Phosphide (GaP) solar cells have been designed, fabricated, characterized and analyzed as candidates for the top junction solar cell in a multi-junction solar cell system. Liquid phase epitaxy (LPE) has been used as the growth method for the epitaxial layers. Open circuit voltage (Voc) of 1.535V has been achieved under one sun illumination from the outdoor test. Quantum efficiency (QE) measurements were used in characterizing our solar cell devices. The QE analysis results show that the high front surface recombination velocity and the low diffusion length in the n-type epi-layer region are the two major limitations for the low Voc and short circuit current density (Jsc). An improved structure has been designed based on our current experimental results.