TITLE

Low-resistance ohmic contacts to p-ZnMgO grown by pulsed-laser deposition

AUTHOR(S)
Hyuck Soo Yang; Li, Y.; Norton, D. P.; Ip, K.; Pearton, S. J.; Soohwan Jang; Ren, F.
PUB. DATE
May 2005
SOURCE
Applied Physics Letters;5/9/2005, Vol. 86 Issue 19, p192103
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Electron-beam deposited Ni/Au is found to produce ohmic contacts to p-type ZnMgO (p∼1016 cm-3) after annealing in the range 300–450 °C. A minimum specific contact resistance of ∼10-2 Ω cm2 at room temperature and of 4×10-5 Ω cm2 at 473 K from circular transmission line measurements was obtained after annealing at 350 °C for 1 min in air. Higher anneal temperatures produced higher contact resistances and reaction of the contact metallurgy with diffusion of Ni to the surface of the Au layer where it became oxidized. The effective barrier height obtained from the measurement temperature dependence of the specific contact resistance, assuming thermionic emission, showed a value of 0.39±0.01 eV, much lower than the theoretical value of ∼2.4 eV. The difference in theoretical and experimental values is a clear indication of the strong role played by surface states, as reported earlier for Au Schottky contacts on ZnO.
ACCESSION #
17164810

 

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