4Power (United States)

Metamorphic GaAs 0.9 P 0.1 tunnel diodes, designed for application to heteroepitaxial GaInP/GaAsP/Si multijunction solar cells, were grown on compositionally graded GaAs y P 1-y /GaAs buffers by molecular beam epitaxy. Optimal growth conditions for high impurity doping were determined and tested using fabricated tunnel diode structures. Peak current densities of 103.9 A · cm -2 and resistance-area products of 4.5 × 10 -4 Ω · cm 2 were obtained. Strong agreement between simulated and fabricated devices indicates excellent device quality with respect to optimized growth conditions and near-nominal operation. These results suggest that the optimized structures are promising for use within III-V/Si multijunction solar cells operating under high concentration.