Planar metal–insulator–metal diodes based on the Nb/Nb2O5/X material system

Abstract

The authors report the performance of various planar metal–insulator–metal (MIM) tunneling diodes, which are being investigated for use in rectenna devices for energy harvesting applications. Six cathode materials (M2): Nb, Ag, Cu, Ni, Au, and Pt are studied in conjunction with Nb as the anode (M1) and Nb2O5 (I) as the dielectric. The cathode materials selections were based on results from a prior rapid-screening study that employed a bent-wire metal cathode point-contact method. Planar devices, to enable analysis using standard MIM diode models, were fabricated with the resultant current density–voltage data obtained at both room temperature and 77 K. The tunnel barrier heights and dielectric properties for these systems were extracted from the modeling results. Nb/Nb2O5/Pt MIM diodes showed the best performance with an asymmetry ratio greater than 7700, a nonlinearity value of 4.7, and a responsivity of 16.9, all at 0.5 V and 300 K. These results confirm prior rapid-screening efforts and further validate the Nb/Nb2O5/Pt system in particular as a promising MIM architecture due to the low barrier height of the junction.