1.5 eV GaInAsP Solar Cells Grown via Hydride Vapor‐Phase Epitaxy for Low‐Cost GaInP/GaInAsP//Si Triple‐Junction Structures

Abstract

Multijunction solar cells combining III–V and Si materials can provide high photoelectric conversion efficiency. Two‐terminal III–V//Si triple‐junction solar cells with an efficiency of 35.9% have already been developed using metal–organic vapor‐phase epitaxy and the direct wafer bonding technique. This study, however, proposes the low‐cost fabrication of III–V solar cells using hydride vapor‐phase epitaxy (HVPE). GaInAsP solar cells are fabricated using HVPE to apply to middle cells in III–V//Si triple‐junction structures. By controlling the partial pressure of the precursors, the optimal bandgap energy of 1.5 eV is obtained for the HVPE‐grown GaInAsP quaternary alloys. The 1.5 eV GaInAsP single‐junction solar cells show higher open‐circuit voltage than the HVPE‐grown GaAs solar cells. The open‐circuit voltage of the GaInAsP solar cells fabricated with a GaInAsP growth rate of 77.6 μm h−1 reaches 1.1 V upon the formation of the rear‐heterojunction structure. In addition, the external quantum efficiency spectra of the HVPE‐grown GaInP/GaInAsP dual‐junction solar cells show that the 1.5 eV GaInAsP solar cells are superior to the GaAs solar cells in terms of current matching for subcells in the III–V//Si triple‐junction structures.