Reverse bias current–voltage measurements of ∼100-μm-diameter gold Schottky contacts deposited on as-received, n
wafers and those exposed for 30 min to a remote 20% O2/80%
He plasma at 525±20 °C
and cooled either in vacuum from 425 °C or the unignited plasma gas have been determined. Plasma cleaning resulted in highly ordered, stoichiometric, and smooth surfaces. Contacts on as-received material showed μA leakage currents and ideality factors >2. Contacts on plasma-cleaned wafers cooled in vacuum showed ∼ 36±1 nA
leakage current to −4 V, a barrier height of 0.67±0.05 eV,
and an ideality factor of 1.86±0.05.
Cooling in the unignited plasma gas coupled with a 30 s exposure to the plasma at room temperature resulted in decreases in these parameters to ∼20 pA to −7 V, 0.60±0.05 eV,
respectively. Differences in the measured and theoretical barrier heights indicate interface states. (0001) and (000)
are used in this letter to designate the polar zinc- and oxygen-terminated surfaces, respectively. © 2003 American Institute of Physics.