Search

Simultaneous scanning Bragg contrast and small-angle ptychographic imaging of a single solar cell nanowire are demonstrated, using a nanofocused hard X-ray beam and two detectors. The 2.5 µm-long nanowire consists of a single-crystal InP core of 190 nm diameter, coated with amorphous SiO2 and polycrystalline indium tin oxide. The nanowire was selected and aligned in real space using the small-angle scattering of the 140 × 210 nm X-ray beam. The orientation of the nanowire, as observed in small-angle scattering, was used to find the correct rotation for the Bragg condition. After alignment in real space and rotation, high-resolution (50 nm step) raster scans were performed to simultaneously measure the distribution of small-angle scattering and Bragg diffraction in the nanowire. Ptychographic reconstruction of the coherent small-angle scattering was used to achieve sub-beam spatial resolution. The small-angle scattering images, which are sensitive to the shape and the electron density of all parts of the nanowire, showed a homogeneous profile along the nanowire axis except at the thicker head region. In contrast, the scanning Bragg diffraction microscopy, which probes only the single-crystal InP core, revealed bending and crystalline inhomogeneity. Both systematic and non-systematic real-space movement of the nanowire were observed as it was rotated, which would have been difficult to reveal only from the Bragg scattering. These results demonstrate the advantages of simultaneously collecting and analyzing the small-angle scattering in Bragg diffraction experiments. [ABSTRACT FROM AUTHOR]

Submicron sized sensors could allowhigher resolution in X-ray imaging and diffraction measurements, whichare ubiquitous for materials science and medicine. We present electricalmeasurements of a single 100 nm diameter InP nanowire transistor exposedto hard X-rays. The X-ray induced conductance is over 5 orders ofmagnitude larger than expected from reported data for X-ray absorptionand carrier lifetimes. Time-resolved measurements show very long characteristiclifetimes on the order of seconds, tentatively attributed to long-livedtraps, which give a strong amplification effect. As a proof of concept,we use the nanowire to directly image an X-ray nanofocus with submicronresolution. [ABSTRACT FROM AUTHOR]