  Resonant tunneling diodes are formed using AlN/GaN core-shell nanowire
heterostructures grown by plasma assisted molecular beam epitaxy on n-Si(111)
substrates. By using a coaxial geometry these devices take advantage of
non-polar (m-plane) nanowire sidewalls. Device modeling predicts non-polar
orientation should enhance resonant tunneling compared to a polar structure and
that AlN double barriers will lead to higher peak-to-valley current ratios
compared to AlGaN barriers. Electrical measurements of ensembles of nanowires
show negative differential resistance appearing only at cryogenic temperature.
Individual nanowire measurements show negative differential resistance at room
temperature with peak current density of 5*10^5 A/cm^2.
