Poole-Frenkel Effect and Phonon-Assisted Tunneling in GaAs Nanowires

We present electronic transport measurements of GaAs nanowires grown by catalyst Free metal organic chemical vapor deposition Despite the nanowires being doped with a relatively high concentration of substitutional Impurities we find them inordirigtely resistive By measuring sufficiently high aspect ratio nanowires individually in situ we decouple the role of the contacts and show that this semi, insulating electrical behavior is the result of trap mediated carrier transport We observe Poole-Frenkel transport that crosses over to phonon assisted tunneling at higher fields will; a tunneling time found to depend predominantly on fundamental physical constants as predicted by theory By using in situ electron beam irradiation of individual nanowires we probe the nanowire electronic transport when free carriers are made available thus revealing the nature of the contacts