Microwave sensing using metal-insulator-metal diodes based on 4-nm-thick hafnium oxide

In this paper, we present a state-of-the-art metal-insulator-metal (MIM) diode, in which the bottom electrode is made of platinum and the top one of titanium, while the in-between oxide is an atomic layer deposition (ALD)-deposited hafnium oxide (HfO
2
) layer with a thickness less than 4 nm, and a footprint area of few square microns. Provided that such devices are suitable for detection and energy harvesting systems at frequencies where classical Schottky diodes fail to comply with the desired specifications of high cut-off frequency and monolithic integration, the proposed MIM demonstrated to be an excellent detector up to 40 GHz, with a maximum current density of over 2×10
³
A/cm
²
, a measured voltage responsivity of about 500 mV/mW at 10 and 24 GHz, and a minimum noise equivalent power of only 160 pW/√Hz. As such, the HfO
2
-based MIM diode could be used as an efficient low-voltage microwave sensor to detect radiofrequency signals in the upcoming smart 5G transceivers.