AVS 49th International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeP

Paper TF-WeP10
The Effects of Substrate Temperature and Ion Flux on the Opto-electronic Properties of dc Magnetron Sputtered Aluminum-doped Zinc Oxide

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Poster Session
Presenter: N.W. Schmidt, Macalester College
Authors: N.W. Schmidt, Macalester College
T.S. Totushek, Macalester College
W. Kimes, Macalester College
J.R. Doyle, Macalester College
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We present a study of the effects of substrate temperature and ion flux on the opto-electronics properties of reactive dc magnetron sputtered aluminum-doped zinc oxide (AZO). Near-substrate plasma density is varied using an unbalanced magnetron with external coils which allow variation of the ion-to-neutral ratio from 0.2 to 2. The substrates are electrically floating with a floating voltage of about -10 V, implying that the ions have 10 eV of energy upon arrival at the growing film. The ion flux is measured using cylindrical and flat plasma probes. Film quality is characterized by conductivity, visible transmission, x-ray diffraction, scanning electron microscopy, and Hall effect measurements. Film quality is found to be very sensitive to substrate temperature in the range of room temperature to 120 C, with transparency increasing and resistivity decreasing with increasing temperature. Film quality is also improved with increasing near-substrate plasma density up to 120 C. The best films have resistivities less than 0.0004 Ohm-cm with average transmission above 85% in the visible. Film quality maximizes in the range 120 - 150 C and then becomes independent of ion flux. The improvement in film quality observed with increasing ion flux at lower temperatures is similar to that found with increasing temperature. However, careful calibration of the substrate temperature indicates that the beneficial effect of increased ion flux is not simply due to substrate heating, implying that kinetic or momentum transfer effects are also important during ion bombardment.