Photoluminescence Detection of Surface Oxidation Processes on InGaN/GaN Nanowire Arrays

InGaN/GaN nanowire arrays (NWA) exhibit efficient photoluminescence (PL) in the green spectral range, which extends to temperatures well beyond 200 °C. Previous work has shown that their PL is effectively quenched when oxidizing gas species such as O₂, NO₂, and O₃ abound in the ambient air. In the present work we extend our investigations to reducing gas species, in particular to alcohols and aliphatic hydrocarbons with C₁ to C₃ chain lengths. We find that these species give rise to an enhancing PL response which can only be observed when the NWAs are operated at elevated temperature and in reactive synthetic air backgrounds. Hardly any response can be observed when the NWAs are operated in inert N₂ backgrounds, neither at room temperature nor at elevated temperature. We attribute such enhancing PL response to the removal of quenching oxygen and the formation of enhancing water adsorbates as hydrocarbons interact with oxygen species coadsorbed on the heated InGaN surfaces.