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 m(0) and 95 meV, respectively. The I-ds-V-ds characteristics show that the MITTs with 58.5 nm channel length can operate with a current on/off ratio of about 10(7).