Ni-pattern guided GaN nanowire-array humidity sensor with high sensitivity enhanced by UV photoexcitation

We have proposed a simple Ni-pattern guided lateral growth method to fabricate selective-area GaN nanowire array. Ni metal has formed contamination-free and high-quality Schottky-contacted interface with in-situ grown GaN nanowire array. In the RH range from 15% to 85%, its output current has a sharp decrease above two orders of magnitude, exhibiting its ultrahigh RH sensing. Its RH sensitivity has been largely enhanced by UV photoexcitation from 3208% to 10066% at 5V and from 7818% to 24037% at ‑5V, respectively.