Effect of ozone cleaning on Pt/Au and W/Pt/Au Schottky contacts to n-type ZnO

The role of UV ozone cleaning on the characteristics of Pt contacts on n-type (n∼1017cm−3) bulk single-crystal zinc oxide (ZnO) is reported. The contacts are Ohmic for samples that were not exposed to ozone prior to Pt deposition, but exhibit excellent rectifying behavior with ozone cleaning. The ba...

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Bibliographic Details
Published in:Applied surface science 2004-09, Vol.236 (1-4), p.387-393
Main Authors: Ip, K, Gila, B.P, Onstine, A.H, Lambers, E.S, Heo, Y.W, Baik, K.H, Norton, D.P, Pearton, S.J, Kim, S, LaRoche, J.R, Ren, F
Format: Article
Language:English
Subjects:
Barrier height
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
n-type ZnO
Physics
UV ozone cleaning
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Summary:The role of UV ozone cleaning on the characteristics of Pt contacts on n-type (n∼1017cm−3) bulk single-crystal zinc oxide (ZnO) is reported. The contacts are Ohmic for samples that were not exposed to ozone prior to Pt deposition, but exhibit excellent rectifying behavior with ozone cleaning. The barrier height of these contacts obtained from current–voltage measurements was 0.70±0.04eV at 25°C with an ideality factor of 1.49 and a saturation current density of 6.17×10−6Acm−2. There is a significant decrease in surface carbon concentration after the ozone cleaning (29.5at.% down to 5.8at.%, as determined from Auger electron spectroscopy). The measured barrier height for Pt on ZnO is similar to the value reported for both Au and Ag rectifying contacts on this material. By sharp contrast, sputter-deposited W contacts are Ohmic, independent of the use of ozone cleaning and become rectifying after 700°C annealing to repair sputter-induced damage. The barrier height is ∼0.45–0.49eV, with the ozone cleaning producing values at the high end of this range.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2004.05.013