Monolithically grown InxGa1−xAs nanowire on silicon tandem solar cells with high efficiency

Heteroepitaxial integration of III–V and Si has been researched for many years since the Si is the prevalent platform and III–V can be used for light emitting source (i.e., direct bandgap) [1]. Although vertical InAs nanowires (NWs) growth on Si substrate (11.6% lattice mismatch) without catalysts and patterning has been demonstrated by several groups, [2, 3], direct heteroexpitaxial growth of ternary InxGa1−xAs nanowires hasn't been systematically studied yet, in spite of its important spectral coverage in the near infrared range. In this paper, we report the one-dimensional heteroepitaxial growth of dislocation free InxGa1−xAs nanowires on silicon (111) substrate in the entire composition range and demonstrate monolithically grown axial p-n junction tandem solar cells consisting of InxGa1−xAs NWs on Si with an efficiency that well exceeds the planar Si single junction solar cell fabricated using identical process.