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CPM Seminar
Anneli Munkholm
Material Science Department We have carried out real-time studies of metal-organic chemical vapor deposition (MOCVD) growth of GaN using grazing incidence x-ray scattering at the Advanced Photon Source. We studied homoepitaxial growth on GaN(0001) thin-film substrates at temperatures up to 1050°C using trimethyl gallium (TMG) and ammonia as precursors at a reactor pressure of 200 Torr. Intensity oscillations of the crystal truncation rods corresponding to layer-by-layer growth were observed, which allowed the growth rate and growth mode boundaries to be determined as a function of process parameters. In addition, a new surface reconstruction was observed, and its phase boundaries were mapped as a function of temperature and ammonia partial pressure. A structural model with a (sqrt(3) x 2sqrt(3))R30° symmetry shows good agreement with the intensity distribution among the reconstruction peaks.
Monday, October 5th 1998, 15:30 |