is forward‐bias turn‐on angle depends on diode input power, ω is the angular frequency. Finally, planar Schottky diodes are not able to operate at higher frequency of 5 THZ in fact for higher frequency operation, the diode series resistance and junction capacitance must be lower. Moreover, Schottky diodes cannot operate at zero bias therefore they are not useful for harvesting application.
4.6 Ultralow-voltage diodes: Geometric Diode
In a geometric diode, the ballistic movement of electrons, combined with a geometrically asymmetric structure, produces a nonlinear I(V) response. The asymmetric structure of the device forces to flow the charge carriers in one direction only and it rectifies an alternating current. Figure 10 shows an example of an asymmetrically patterned. In contrast with MIM diodes that have parallel plate electrodes, the planar structure of the geometric diode provides a low RC time constant, about 10-15 s, which permits operation at optical frequencies. The resistance of the diodes is also sufficiently low to match the antenna impedance. Charge carriers move from left to right (forward direction) more easily than in the opposite direction because of the funneling effect of the arrowhead shaped edges.