Improved microwave sensitivity to 706 kV/W by using p-GaAsSb/n-InAs nanowire backward diodes for low-power energy harvesting at zero bias

In this study, a p-GaAs0.4Sb0.6/n-InAs nanowire backward diode (NW BWD) with a large sensitivity of 706 kV/W, exceeding that of Schottky barrier diodes (SBDs), was developed for low-power microwave rectification at zero bias. The interband tunneling of the NW BWDs under zero-bias condition displayed a large nonlinear characteristic of typical BWDs, which is effective for realizing power detection with high sensitivity. The fabricated NW BWDs indicated linear detected voltages (Vdet) when a microwave input power (Pin) of ∼1 µW was applied at 2.4 GHz. From the Vdet, Pin, and return loss obtained from the S-parameter measurements, an impedance-matched voltage sensitivity of 706 kV/W was calculated for the NW BWD at zero bias. The obtained sensitivity value was higher than that of a well-designed SBD, which was ∼62 kV/W at 2.4 GHz. According to the extracted device parameters, it was found that to improve the sensitivity of the NW-BWD, not only the junction capacitance of the diode but also the parasitic pad capacitance needs to be reduced. The high sensitivity is attributed to the high curvature coefficient of −26.7 V−1 and the small junction capacitance of the NW structure of the BWD.