Electrical, memristive and hydrogen sensing properties of Al/4H-SiC/metal sandwich MSM devices

In the present study, we investigated the electrical characterization and gas sensing properties of Al/4H-SiC/Metal in metal/semiconductor/metal (MSM) sandwich structures. Top metal contacts were fabricated using Ag, Pt, Pd, Ti and Ni, with DC/AC characteristics analyzed between 25 °C and 160 °C. The Al/4H-SiC/Ag, Al/4H–SiC/Pt and Al/4H-SiC/Pd MSM devices exhibited Schottky diode behavior, with the forward current and barrier heights being critically dependent on the metal type and temperature, in accordance with the thermionic emission model. The Al/4H-SiC/Ti and Al/4H-SiC/Ni MSM devices exhibit Schottky diode characteristics instead of the anticipated ohmic behavior, attributable to the absence of a post-annealing process. The fabricated MSM structures exhibit memristive switching behavior characterized by a voltage-dependent cluster transition toward a low resistance state, suggesting the formation of a stable conducting filament. The Al/4HSiC/Pd MSM device demonstrated significant stability and hydrogen sensing performance, showing a highly reproducible response of 1900 upon exposure to 1% hydrogen.