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Enlargement of step-free SiC surfaces by homoepitaxial web growth of thin SiC cantilevers

2002; American Institute of Physics; Volume: 92; Issue: 5 Linguagem: Inglês

10.1063/1.1497456

1520-8850

Philip G. Neudeck, J. A. Powell, Glenn M. Beheim, Emye L. Benavage, Phillip B. Abel, Andrew J. Trunek, David J. Spry, Michael Dudley, William M. Vetter,

Silicon and Solar Cell Technologies

Lateral homoepitaxial growth of thin cantilevers emanating from mesa patterns that were reactive ion etched into on-axis commercial SiC substrates prior to growth is reported. The thin cantilevers form after pure stepflow growth removes almost all atomic steps from the top surface of a mesa, after which additional adatoms collected by the large step-free surface migrate to the mesa sidewall where they rapidly incorporate into the crystal near the top of the mesa sidewall. The lateral propagation of the step-free cantilevered surface is significantly affected by pregrowth mesa shape and orientation, with the highest lateral expansion rates observed at the inside concave corners of V-shaped pregrowth mesas with arms lengthwise oriented along the 〈11̄00〉 direction. Complete spanning of the interiors of V’s and other mesa shapes with concave corners by webbed cantilevers was accomplished. Optical microscopy, synchrotron white beam x-ray topography and atomic force microscopy analysis of webbed regions formed over a micropipe and closed-core screw dislocations show that c-axis propagation of these defects is terminated by the webbing. Despite the nonoptimized process employed in this initial study, webbed surfaces as large as 1.4×10−3 cm2, more than four times the pregrowth mesa area, were grown. However, the largest webbed surfaces were not completely free of bilayer steps, due to unintentional growth of 3C-SiC that occurred in the nonoptimized process. Further process optimization should enable larger step-free webs to be realized.