title: Dynamic visualization of axial p-n junctions in single gallium nitride nanorods under electrical bias.
abstract: We demonstrate a direct visualization method based on secondary electron (SE) imaging in scanning electron microscopy for mapping electrostatic potentials across axial semiconductor nanorod p-n junctions. It is found that the SE doping contrast can be directly related to the spatial distribution of electrostatic potential across the axial nanorod p-n junction. In contrast to the conventional SE doping contrast achieved for planar p-n junctions, the quasi-one-dimensional geometry of nanorods allows for high-resolution, versatile SE imaging under high accelerating voltage, long working distance conditions. Furthermore, we are able to delineate the electric field profiles across the axial nanorod p-n junction as well as depletion widths at different reverse biases. By using standard p-n junction theory and secondary ion mass spectroscopy, the carrier concentrations of p- and n-regions can be further extracted from the depletion widths under reverse biasing conditions. This direct imaging method enables determination of electrostatic potential variation of p-n junctions in semiconductor nanorod and nanowire devices with a spatial resolution better than 10 nm.
authors.affiliation: Department of Physics, National Tsing-Hua University , Hsinchu 30013, Taiwan.
authors.forename: Yu-Jung
authors.initials: YJ
authors.lastname: Lu
authors.forename: Ming-Yen
authors.initials: MY
authors.lastname: Lu
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Yang
authors.forename: Hung-Ying
authors.initials: HY
authors.lastname: Chen
authors.forename: Lih-Juann
authors.initials: LJ
authors.lastname: Chen
authors.forename: Shangjr
authors.initials: S
authors.lastname: Gwo