June 2018

Classical boundary scattering in semiconducting InAs nanowires: Semiconducting nanowires are of great importance as nano-devices for future electronic and optoelectronic applications, such as e.g. field-effect transistors, gas sensors or light-emitting diodes. Such semiconductor nanowires are typically one micrometer in length and have a diameter in the range of less than one hundred nanometer. On these small dimensions, the nanowires also show interesting quantum-mechanical transport phenomena. The figure shows the change of the electrical resistance of a single InAs nanowire in an applied external magnetic field for an orientation of the field parallel and perpendicular to the axis. Typically, semiconductors exhibit a quadratic magnetoresistance, whereby the resistance should be linear with the square of the field. This is indeed the case for a parallel orientation of the field to the wire. However, if the external field is oriented perpendicular to the nanowire, the resistance exhibits a kink. This behavior indicates additional scattering of the electrons at the interfaces of the nanowire. Due to the field perpendicular to the direction of the current the electrons are deflected by the Lorentz force on circular paths. In the case of small fields, the electrons scatter at the interface (classical interface scattering) resulting in an additional contribution to the magnetoresistance (region I). Increasing the field reduces the radius of the circular path due to the stronger Lorentz force and increases the probability of backscattering. Above a certain critical magnetic field strength, the radius of the circular path becomes smaller than the diameter of the wire and the contribution of the interface scattering decreases (region II), which leads to the kink in the magnetic resistance. (Picture submitted by Patrick Uredat and Matthias Elm.)