CPM Seminar

Mapping Semiconductor Nanowire Junction Potentials

Karen Kavanagh

Department of Physics
Simon Fraser University

Free-standing semiconductor nanowires (NWs) formed via epitaxial growth from a substrate often have a well-controlled bottom-end connection. Electrical probing via a top contact, perhaps a catalyst particle, can be carried out directly using in-situ methods in electron microscopes. In this way, we have obtained current-density-voltage (J-V) characteristics and electron-beam-induced current (EBIC) measurements, from many different types of semiconductor NWs. [1, 2] The presence of space-charge regions at axial and radial, dopant-concentration gradients (p-n junctions) can also be mapped via measurement of electron-beam phase shifts using electron holography. [3, 4] This talk will describe results from GaAs, InP and Si NW p-n junctions.

[1] Rectifying characteristics of Te-doped GaAs nanowires, O. Salehzadeh, M. X. Chen, K.L. Kavanagh, S. P. Watkins, Appl. Phys. Lett. 99, 182102 (2011).
[2] Axial EBIC oscillations at core/shell GaAs/Fe nanowire contacts, Mingze Yang, David Dvorak, Karin Leistner, Christine Damm, S P Watkins and K L Kavanagh, Nanotechnology 30 (2019) 025701.
[3] Direct Measurement of the Electrical Abruptness of a Nanowire p−n Junction, Ali Darbandi, James C. McNeil, Azadeh Akhtari-Zavareh, Simon P. Watkins, and Karen L. Kavanagh, Nano Letters 16, (2016) 3982−3988.
[4] Three-dimensional imaging of beam-induced biasing of InP/GaInP tunnel diodes, Cristina Cordoba, Xulu Zeng, Daniel Wolf, Axel Lubk, Enrique Barrigon, Magnus T. Borgström, and Karen L. Kavanagh, Nano Letters 196 (2019) 3490.