AVS 46th International Symposium
    Electronic Materials and Processing Division Monday Sessions
       Session EM-MoM

Paper EM-MoM3
Mechanisms for Lateral Growth and Coalescence in GaN CVD

Monday, October 25, 1999, 9:00 am, Room 608

Session: Nitride Epitaxy
Presenter: M.E. Bartram, Sandia National Laboratories
Authors: M.E. Bartram, Sandia National Laboratories
M.E. Coltrin, Sandia National Laboratories
J. Han, Sandia National Laboratories
C.C. Willan, Sandia National Laboratories
Correspondent: Click to Email
Recent observations of rapid coalescence occurring upon convergence of lateral growth fronts suggest new strategies for GaN selective area growth (SAG) techniques. A mask with systematically spaced nucleation zones was used to provide a pseudo time-base for observing lateral growth transitions within a single GaN deposition. Scanning electron microscopy (SEM) revealed that the joining of adjacent features initiated a secondary lateral growth mechanism. The profile of the coalescence region suggests this rapid mode of deposition was controlled by layer-by-layer growth in which each new growth surface defined a reactive step against the initial growth front for nucleation of the next layer. This buildup thus driven by the lateral rate, resulted in the vertical growth front in the coalescence region meeting the upper most surface of the initial growth features. The layer-by-layer coalescence mechanism was quite independent of the slower progress of the original growth fronts when the V/III ratio was sufficiently high. However, it was non-existent under low V/III conditions. Correlations with materials quality will be made using TEM and CL measurements.