Pseudodirect to Direct Compositional Crossover in Wurtzite GaP/InxGa1-xP Core-Shell Nanowires.

Thanks to their uniqueness, nanowires allow the realization of novel semiconductor crystal structures with yet unexplored properties, which can be key to overcome current technological limits. Here we develop the growth of wurtzite GaP/InxGa1-xP core-shell nanowires with tunable indium concentration and optical emission in the visible region from 590 nm (2.1 eV) to 760 nm (1.6 eV). We demonstrate a pseudodirect (Γ8c-Γ9v) to direct (Γ7c-Γ9v) transition crossover through experimental and theoretical approach. Time resolved and temperature dependent photoluminescence measurements were used, which led to the observation of a steep change in carrier lifetime and temperature dependence by respectively one and 3 orders of magnitude in the range 0.28 ± 0.04 ≤ x ≤ 0.41 ± 0.04. Our work reveals the electronic properties of wurtzite InxGa1-xP.