Material studies regarding InP-based high-efficiency solar cells

Aiming at the improvement of the conversion efficiency of a monolithic high-efficiency multi-junction solar cell based on the lattice constant of InP different types of low-band gap n/p solar cells were prepared on the lattice constant of InP via metal organic chemical vapor deposition (MOCVD) using only non-gaseous, so-called alternative precursors like tertiarybutylphosphine (TBP). Employing this less-toxic precursor compared to phosphine an InP single n/p solar cell was prepared as reference yielding the highest internal quantum efficiency reported in the literature. New materials were introduced on the lattice constant of InP, in particular GaAsSb (Egap=0.75eV) and InAlGaAs (Egap=1.03eV). The new absorber materials were compared to more established materials like InGaAs (Egap=0.75eV) and InGaAsP (Egap=1.03eV). It will be shown that the latter cell with 18% Al reached an internal quantum efficiency close to that of the InGaAsP cell.