Carrier Recombination in the Base, Interior, and Surface of InAs/InAlAs Core-Shell Nanowires Grown on Silicon.

We report on carrier recombination within self-catalyzed InAs/InAlAs core-shell nanowires (NWs), disentangling recombination rates at the ends, sidewalls, and interior of the NWs. Ultrafast optical pump-probe spectroscopy measurements were performed from 77-293 K on the free-standing, variable-sized NWs grown on lattice-mismatched Si(111) substrates, independently varying NW length and diameter. We found NW carrier recombination in the interior is nontrivial compared to the surface recombination, especially at 293 K. Surface recombination is dominated by carrier recombination at the NW sidewall, while contributions from the highly strained, impure NW base are negligible.