Schottky and tunneling behavior of Fe/MgO/Ge(100) structures

We investigated interface and electrical properties of Ge-based Schottky and tunnel diodes with crystalline MgO barriers. Following a simple cleaning procedure not requiring a high-temperature anneal, x-ray data indicated smooth interfaces and that the MgO tunnel barrier was highly textured. Transport characteristics were fitted using a self-consistent field Simmons-Schottky current-voltage model, yielding the Schottky and tunnel barrier heights for the devices and the distribution of tunneling currents. Considering the Fermi-level depinning and the ratio of Schottky to tunneling currents for each barrier thickness, we find that a MgO thickness of 15 angstrom yields the best transport properties in this system. (C) 2010 American Institute of Physics. [doi:10.1063/1.3518071]