n-GaAlAs on p-GaAs heterostructure solar cells grown by molecular beam epitaxy

p-GaAs substrate was used as the starting material in molecular beam epitaxial growth. n-type GaAlAs for heterostructure and n-GaAs capping layer were then grown after a buffer layer deposition on the substrate. The n-GaAlAs on p-GaAs heterostructure solar cells, with active area of 13.25 mm2 under 100 mW/cm2 AM1 illumination light source, provide a typical output as follows: Voc=0.73 V, Isc=6 mA, FF=0.7 and η=23% (active area). Spectral response measurements from 500 to 850 nm reflects the window effect of GaAlAs and band edge of GaAs materials.