title: In Situ Chemical Modification of Schottky Barrier in Solution-Processed Zinc Tin Oxide Diode.
abstract: Here we present a novel in situ chemical modification process to form vertical Schottky diodes using palladium (Pd) rectifying bottom contacts, amorphous zinc tin oxide (Zn-Sn-O) semiconductor made via acetate-based solution process, and molybdenum top ohmic contacts. Using X-ray photoelectron spectroscopy depth profiling, we show that oxygen plasma treatment of Pd creates a PdOx interface layer, which is then reduced back to metallic Pd by in situ reactions during Zn-Sn-O film annealing. The plasma treatment ensures an oxygen-rich environment in the semiconductor near the Schottky barrier, reducing the level of oxygen-deficiency-related defects and improving the rectifying contact. Using this process, we achieve diodes with high forward current density exceeding 10(3)A cm(-2) at 1 V, rectification ratios of >10(2), and ideality factors of around 1.9. The measured diode current-voltage characteristics are compared to numerical simulations of thermionic field emission with sub-bandgap states in the semiconductor, which we attribute to spatial variations in metal stoichiometry of amorphous Zn-Sn-O. To the best of our knowledge, this is the first demonstration of vertical Schottky diodes using solution-processed amorphous metal oxide semiconductor. Furthermore, the in situ chemical modification method developed here can be adapted to tune interface properties in many other oxide devices.
authors: Department of Electrical Engineering and Computer Science, University of Michigan , Ann Arbor, Michigan 48109-2122, United States.
authors: Youngbae
authors: Y
authors: Son
authors: Department of Electrical Engineering and Computer Science, University of Michigan , Ann Arbor, Michigan 48109-2122, United States.
authors: Jiabo
authors: J
authors: Li
authors: Department of Electrical Engineering and Computer Science, University of Michigan , Ann Arbor, Michigan 48109-2122, United States.
authors: Rebecca L
authors: RL
authors: Peterson
keywords: Schottky diode; amorphous metal oxide; interface chemistry; oxygen vacancy; solution process