  The Schottky diode, BN/GaN layered composite contacting to bulk aluminum, is
theoretically plausible to harvest wireless energy above X-band. According to
our first principle calculation, the insertion of GaN layers dramatically
influences the optical properties of the layered composite. The relative
dielectric constant of BN/GaN layered composite as a function of layer-to-layer
separation is investigated where the optimized dielectric constant is 3.1.
Furthermore, we design another Schottky diode via nanostructuring. Our first
principle calculation suggests that the relative dielectric constant of boron
nitride monolayer can be minimized to 1.5 only if it is deposited on aluminum
monolayer. It is rare to find a semiconductor with the dielectric constant
close to 1 which may push the cut-off frequency of Al/BN-based rectenna to the
high-band 5G network.
