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Fabrication of stable, wide-bandgap thin films of Mg, Zn and O

United States Patent

July 25, 2006
View the Complete Patent at the US Patent & Trademark Office
A stable, wide-bandgap (approximately 6 eV) ZnO/MgO multilayer thin film is fabricated using pulsed-laser deposition on c-plane Al.sub.2O.sub.3 substrates. Layers of ZnO alternate with layers of MgO. The thickness of MgO is a constant of approximately 1 nm; the thicknesses of ZnO layers vary from approximately 0.75 to 2.5 nm. Abrupt structural transitions from hexagonal to cubic phase follow a decrease in the thickness of ZnO sublayers within this range. The band gap of the thin films is also influenced by the crystalline structure of multilayer stacks. Thin films with hexagonal and cubic structure have band-gap values of 3.5 and 6 eV, respectively. In the hexagonal phase, Mg content of the films is approximately 40%; in the cubic phase Mg content is approximately 60%. The thin films are stable and their structural and optical properties are unaffected by annealing at C.
Katiyar; Ram S. (San Juan, PR), Bhattacharya; Pijush (San Juan, PR), Das; Rasmi R. (San Juan, PR)
University of Puerto Rico (San Juan, PR)
10/ 932,656
September 2, 2004
GOVERNMENT SPONSORED RESEARCH The subject invention was supported, in part, by a grant from the Department of Energy through grant nos. DE-F6-02--01ER45868 and NCC3-1034.