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 inordinately 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, with 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.
Sandia National Laboratories, Livermore, California 94551, United States.
Aaron M
AM
Katzenmeyer
François
F
Léonard
A Alec
AA
Talin
Ping-Show
PS
Wong
Diana L
DL
Huffaker