Figure 1

Detailed morphological and optical properties of InGaN NWs.
(a) Tilted FE-SEM image of the as-grown InGaN NWs on the r-plane sapphire substrate. (b) Magnified cross-sectional image for an ensemble of InGaN NWs showing their orientation and their tapered geometry. (c) High magnification top-view SEM image showing the triangular cross-section of an InGaN NW. (d) Large scale top-view SEM image of the as-grown InGaN NWs with good substrate coverage. (e) Room-temperature PL spectra of InGaN NWs as a function of the In/Ga molar flow ratio. (f) Schematic illustration of the energy band diagram of UIF NWs showing the shallow and deep localized states and the corresponding blue and green PL emissions.