Epitaxially-grown metamorphic GaAsP/Si dual-junction solar cells

The development and demonstration of methodologies for the heteroepitaxy of GaP on Si substrates, free of heterovalent interface related defects, and the subsequent metamorphic grading in the GaAs_yP_1-y alloy system necessary to achieve target III-V materials at sufficiently high quality, directly enable the achievement of monolithically-integrated multijunction solar cells utilizing both III-V and Si active sub-cells. Such devices hold promise for high photovoltaic performance at significantly reduced costs afforded by the Si platform. In this vein, early-stage prototype all-epitaxial GaAs_0.75P_0.25/Si dual-junction devices have been grown by a combination of MOCVD and MBE, demonstrating great promise for such an approach, and clear pathways for further improvement.