InGaAs GaAsSb tunnel junction employed in a low band gap tandem solar cell

Monolithically, MOCVD grown low band gap tandem solar cells composed of InGaAs Eg 0.75 eV and InGaAsP Eg 1.05 eV , lattice matched to InP were investigated. The subcells in the tandem structure are connected in series via a tunnel diode using n InGaAs and p GaAsSb. For improving the growth process and, thus, improving the cell performance the InGaAs GaAsSb hetero interface was studied with low energy electron diffraction LEED and x ray photoemission spectroscopy XPS . Secondly, the growth conditions for the GaAsSb InP hetero interface were investigated. First measurements of the low band gap tandem solar cells are shown. The low band gap tandem structure has been designed for operation below a high band gap tandem cell GaA