2-TERMINAL MONOLITHIC INP INGAASP TANDEM SOLAR-CELLS WITH TUNNELING INTERCELL OHMIC CONNECTIONS/

In order to explore the potential of InP based material for multijunct ion tandem solar cell applications, a two-terminal monolithic InP/InGa AsP tandem solar cell was prepared by two-step liquid phase epitaxial (LPE) growth and their photovoltaic properties were characterized. The series-connected tandem solar cell consists of a 1.35 eV p/n homojunc tion InP top subcell and a lattice matched 0.95 eV p/n homojunction In GaAsP bottom subcell. A patterned 0.95 eV n(+)/p(+) InGaAsP tunnel dio de was employed as intercell ohmic connections (IOCs). The open-circui t voltage, short-circuit current and fill factor exhibited by the most efficient InP/InGaAsP tandem solar cell under one sun, AM1.5 global i lluminations were 1.363 V, 13.85 mA/cm(2) and 0.786, respectively; wit h a total-area conversion efficiency of 14.8%. Further improvements in conversion efficiencies may be obtained by depositing a wide bandgap GaInP top subcell to the existing InP/InGaAsP tandem structure to form a two terminal monolithic GaInP/InP/InGaAsP tandem solar cell. Some o f the technical issues concerning three-junction InP-based tandem sola r cells are discussed.