AVS 45th International Symposium
    Selected Energy Epitaxy Topical Conference Thursday Sessions
       Session SE-ThA

Paper SE-ThA5
The Effect of Scaling Precursor Duty Cycles on Pulsed Supersonic Molecular Beam AlN Growth Rates

Thursday, November 5, 1998, 3:20 pm, Room 327

Session: Seeded Supersonic Beam Epitaxial Growth
Presenter: V.W. Ballarotto, Ohio University
Authors: V.W. Ballarotto, Ohio University
M.E. Kordesch, Ohio University
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The effect of varying the precursor duty cycles for AlN grown on Si (100) at 650 °C with pulsed supersonic molecular beams is reported. The duty cycle is defined as the on-time of the valve multiplied by the driving frequency. The Al precursor was trimethylaluminum (130 meV) and the N precursor was 5 percent ammonia seeded in He (220 meV). The duty cycle was varied by changing the driving frequency. The growth rate of AlN films increases linearly (0.09 µ/h to 0.50 µ/h) with an increase in driving frequency. However, the growth rate in terms of thickness per pulse is roughly constant (1 Å/pulse). Total film thickness is on the order of 1-2 µ. A comparison of the growth rates when the duty cycle is varied by changing valve on-time will be presented. The films are predominantly oriented with the non-polar (10-0) plane parallel to the substrate plane. Preliminary results from x-ray diffraction @phi@ scans show that the films exhibit a preferred orientation that does not depend on substrate orientation or film thickness. The nucleation and growth of the non-polar (10-0) film face on polar (0001) MOCVD AlN will be discussed. Support provided by BMDO/ONR N00014-96-1-0782 and -1060.