Regensburg 2019 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 2: Focus Session: Oxide Semiconductors for Novel Devices (joint session HL/DS)

DS 2.6: Hauptvortrag

Montag, 1. April 2019, 12:15–12:45, H34

Nanoscale Control of Native Point Defects and Doping in Oxide Semiconductors — •Leonard Brillson — The Ohio State University, Columbus, OH, USA

Nanoscale optical and electrostatic techniques can directly measure the movement of native point defects inside oxide semiconductors and how they control space charge regions, tunneling, and contact rectification. Depth-resolved cathodoluminescence spectroscopy (DRCLS) with hyperspectral imaging measures 3-dimensional defect redistribution on a nanoscale for ZnO, Ga2O3, SrTiO3, and BaSrTiO3, revealing how intrinsic and applied electric fields drive defect movement. Defects at metal-ZnO diodes change carrier densities, tunneling, and trap-assisted hopping, altering Zn- vs. O-polar Schottky barriers. Nanoscale 3D measurement and imaging reveal electrically-active defects that extend deep inside wires, altering depletion widths, conducting channel volumes, and metal-ZnO nano-contact rectification. Electron and ion beams alter defect distributions to create rectifying, ohmic, or blocking contacts with the same metal on the same nanowire, demonstrating the interplay between the nature of native point defects, the intrinsic doping, and the physical dimensions of the nanostructure itself in determining the electronic properties of the oxide interface. DRCLS also enabled us to correlate the dominant luminescence features of Ga2O3 with the most thermodynamically stable O vacancy, Ga vacancy, and Ga vacancy-hydrogen defect states in the band gap predicted theoretically. As with ZnO, the combined depth-resolved detection and processing of Ga2O3 suggests new avenues for defect and doping control.