Four-junction heterovalent solar cells based on II-VI/III-V/Ge coherent and metamorphic heterostructures

Abstract

We present original design and performance simulations of four-junction heterovalent concentrator solar cells with monolithically integrated junctions based on Ge, III–V, and II–VI semiconductors. The developed design relies on the formation of a metamorphic buffer layer matching lattice constants of a Ge junction and three more junctions based on InGaAs, AlInGaAs, and a ZnSe/CdSe short-period superlattice. Utilizing of an n+-type chlorine-doped layer of ZnCdMgSe as a highly transparent conductive window is proposed. Experimental results are reported, demonstrating the potential of molecular beam epitaxy to fabricate such solar cell heterostructures atop of a Ge p–n junction formed in a Ge substrate.