SEM images and SIMS and EDX spectra. (a) Low and (b) high magnification SEM images of the undoped ZnO nanorods (#1). (c) SEM image and (e) SIMS spectrum of trace In-doped ZnO NWs (#2). (d) SEM image of high content In-doped ZnO NWs (#3). (f) EDX spectrum of individual NW in sample #3.