19 research outputs found
Photocurrent and Photoconductance Properties of a GaAs Nanowire
We report on photocurrent and photoconductance processes in a freely
suspended p-doped single GaAs nanowire. The nanowires are grown by molecular
beam epitaxy (MBE), and they are electrically contacted by a focused ion beam
(FIB) deposition technique. The observed photocurrent is generated at the
Schottky contacts between the nanowire and metal source-drain electrodes, while
the observed photoconductance signal can be explained by a photogating effect
induced by optically generated charge carriers located at the surface of the
nanowire. Both optoelectronic effects are sensitive to the polarization of the
exciting laser field, enabling polarization dependent photodetectors
Photo-acoustic spectroscopy revealing resonant absorption of self-assembled GaAs-based nanowires
Hard X-ray Detection Using a Single nm Diameter Nanowire
Submicron sized sensors could allow higher resolution in X-ray imaging and diffraction measurements, which are ubiquitous for materials science and medicine. We present electrical measurements of a single 100 nm diameter InP nanowire transistor exposed to hard X-rays. The X-ray induced conductance is over 5 orders of magnitude larger than expected from reported data for X-ray absorption and carrier lifetimes. Time-resolved measurements show very long characteristic lifetimes on the order of seconds, tentatively attributed to long-lived traps, which give a strong amplification effect. As a proof of concept, we use the nanowire to directly image an X-ray nanofocus with submicron resolution