Physics Commons^™

Metamorphic Gaasp Buffers For Growth Of Wide-Bandgap Ingap Solar Cells, J. Simon, S. Tomasulo, P. J. Simmonds, M. Romero, M. L. Lee

Paul J. Simmonds

GaAs_xP_1−x graded buffers were grown via solid source molecular beam epitaxy(MBE) to enable the fabrication of wide-bandgap In_yGa_1−yP solar cells. Tensile-strained GaAs_xP_1−x buffers grown on GaAs using unoptimized conditions exhibited asymmetric strain relaxation along with formation of faceted trenches, 100–300 nm deep, running parallel to the [011] direction. We engineered a 6 μm thick grading structure to minimize the faceted trench density and achieve symmetric strain relaxation while maintaining a threading dislocation density of ≤10⁶ cm⁻². In comparison, compressively-strained graded GaAs_xP_1−x buffers on …