Platinum (Pt), gold (Au), and silver (Ag) ohmic contacts to cupric oxide (CuO) films deposited by air-based sputtering and thermal annealing

The present work reports the fabrication of three different ohmic contacts (platinum (Pt)/CuO, gold (Au)/CuO, and silver (Ag)/CuO). Structural properties of the films measured by X-ray diffraction and Raman techniques confirmed that the Cu2O films prepared by DC sputtering using air as a reactive gas, transformed into pure CuO films after thermal annealing. The band gap of the CuO films of 1.33 eV was estimated by reflectance measurements. Hall measurements confirmed the p-type conductivity of the CuO films with an acceptor concentration of 2.04x1016 cm−3.The linear behavior in both directions of polarization observed in the current–voltage measurements confirmed the formation of ohmic contacts between the characterized three metals and CuO. Based on the slope of the current–voltage curve, the best ohmic contact was that fabricated between Au and CuO. The mechanism governing the transport through the interface between the metal/CuO ohmic contact was thermionic emission.