Electrical characterization of tunnel insulator in metal/insulator tunnel transistors fabricated by atomic force microscope
Metal-insulator-tunnel-transistors (MITTs) that operate by varying the gate voltage to control the current flow through a tunnel insulator were fabricated. In this work, the local Ti/TiOx/Ti tunnel junctions were formed by tip-induced anodic oxidation using conducting-tip atomic force microscope. Experimental results show that the dominant conduction mechanism of the Ti/TiOx/Ti structure at 300 K is Schottky emission at low electric field and Fowler–Nordheim tunneling at high electric field, respectively. The Ti/TiOx barrier height and the electron effective mass in TiOx are evaluated using both the intercept of Schottky plot and the slope of Fowler–Nordheim plot. The electron effective mass in TiOx and the extracted Ti/TiOx barrier height were determined to be 0.48 m0 and 95 meV, respectively. The Ids-Vds characteristics show that the MITTs with 58.5 nm channel length can operate with a current on/off ratio of about 107.