Subliming GaN into ordered nanowire arrays for ultraviolet and visible nanophotonics

We report on the fabrication of ordered arrays of InGaN/GaN nanowire quantum disks by a top-down selective-area sublimation method. Using a combination of two-dimensional molecular beam epitaxy of InGaN/GaN quantum wells, electron-beam lithography and ultra-high-vacuum sublimation techniques, we demonstrate that the position, geometry and dimensions of nanowires can be finely controlled at nano-, micro- and macro-scales. Relying on a large set of structural data, we evaluate in particular the relative sublimation rates of GaN crystal planes that drive the nanowire formation, we assess the intrinsic limits of selective area sublimation for the fabrication of NW arrays and we evaluate the homogeneity of the process across the wafer. Because the sublimation method preserves the crystal quality of the NW material, we show that InGaN/GaN NWs present good optical properties, which can be leveraged for photonic applications in the ultraviolet and the visible range. In particular, we demonstrate that it is possib...