AVS 56th International Symposium & Exhibition
    Electronic Materials and Processing Thursday Sessions
       Session EM-ThM

Paper EM-ThM6
Cyclic In-Situ Deposition and Etching for Growth of High-Quality Zinc Oxide by Metalorganic Chemical Vapor Deposition

Thursday, November 12, 2009, 9:40 am, Room B1

Session: Oxide Semiconductors
Presenter: E.J. Adles, NC State University
Authors: E.J. Adles, NC State University
D.E. Aspnes, NC State University
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Zinc oxide (ZnO) is a transparent conducting oxide with a room-temperature band gap of 3.37 eV. It is currently under investigation for magneto-optic applications and as a cheap alternative for optic and optoelectronic devices currently depending on gallium and indium. While epitaxial ZnO can be grown by a number of laboratory-scale methods, growth by industrial-scale processes such as metalorganic chemical vapor deposition (MOCVD) is hampered by particulate ZnO formed in the gas phase and by the natural tendency of ZnO to deposit in multiple orientations. Both prevent deposition of high-quality epitaxial material. After careful consideration of gas-phase chemistry and our real-time polarimetric data, we have developed a cyclic MOCVD growth process based entirely on diethylzinc where conditions are alternated between brief periods of deposition and etching. The gas-phase particles are used as the source of ZnO. The etching part of the cycle preferentially removes unwanted orientations, since these typically have higher free energies. The result is dense two-dimensional epitaxial ZnO. Because etching is driven chemically instead of thermally, infilling and smoothing occur at much lower temperatures and shorter time scales than previously discussed in the literature.