| AVS 60th International Symposium and Exhibition | |
| Transparent Conductors and Printable Electronics Focus Topic | Wednesday Sessions |
| Session TC+EM+EN+TF-WeA |
| Session: | Transparent Conductors and Photovoltaics |
| Presenter: | B. Krueger, University of Washington |
| Authors: | B. Krueger, University of Washington N. Nguyen, National Institute for Materials Science, Japan T. Chikyow, National Institute for Materials Science, Japan F.S. Ohuchi, University of Washington M.A. Olmstead, University of Washington |
| Correspondent: | Click to Email |
Gallium oxide is a transparent semiconductor (Eg ~ 4.8 eV) that exhibits n-type conductivity; it has been proposed for a variety of uses ranging from “solar-blind” conductive coatings to chemical sensing. An intriguing possibility is development of transparent, high power transistors based on carrier accumulation at an epitaxial Ga2O3–(AlxGa1-x)2O3 alloy interface. Using pulsed laser deposition, combinatorial (AlxGa1-x)2O3 thin films were fabricated on a variety of substrates, including sapphire, GaN, SrTiO3 and LaAlO3, with x varying smoothly across the surface. Position-dependent X-ray diffraction revealed [-201]-oriented Ga2O3 on hexagonal GaN (0001) surfaces (5% lattice mismatch) and predominantly [-201]-oriented on c-plane sapphire (8% mismatch). Alloy (AlxGa1-x)2O3 films remain in the β-Ga2O3 phase for 0 < x < 0.15 on GaN and 0 < x < 0.35 on sapphire, with negligible lattice expansion; a new alloy phase is observed for 0.15 < x < 0.35 on GaN. Photoemission spectroscopy shows core and valence levels both shift to higher binding energy with increasing Al concentration, and the work function decreases, consistent with a widening band gap.
This work was supported by the National Science Foundation under DMR 1104628 and OISE 1209856 and by the Micron Foundation.