ELSEVIER Journal of Crystal Growth 154 (1995) 72-80 ......... CRYSTAL GROWTH Epitaxial growth of SiC thin films on Si-stabilized a-SiC(0001) at low temperatures by solid-source molecular beam epitaxy A. Fissel *, U. Kaiser, E. Ducke, B. Schr6ter, W. Richter lnstitut fiir FestkOrperphysik, Friedrich-Schiller-Uniuersita'tJena, Max-Wien-Platz 1, D-07743 Jena, Germany Received 24 February 1995; manuscript received in final form 4 April 1995 Abstract Epitaxial growth of SiC on a-SiC(0001) substrates was carried out at relatively low temperatures (900-1000°C) and high growth rates (about 1 nm/min), by means of solid-source molecular beam epitaxy controlled by a quadrupole mass spectrometry based flux meter. The films were obtained on silicon-stabilized surfaces showing (3 x 3) and (2 x 2) superstructures. The reflection high-energy electron diffraction (RHEED) and transmission electron microscopy (TEM) investigations show, independent of the surface orientation, that the film growth can be quantified in two steps: In the initial stage of growth, at first the Si-determined superstructure will be formed. Despite the low temperature, growth of SiC then proceeds in a layer-by-layer mode leading to flat film-substrate interfaces. This result demonstrates the significance of surface reconstruction for the growth process, corresponding to results recently obtained using gas source molecular beam epitaxy. The films grow by stacking of laminae of a- and /3-SIC, respectively, which may be attributed to fluctuations in the Si adlayer thickness. Films grown on off-oriented substrates contain many defects, likely double-positioning boundaries, directly associated with surface steps. For increasing film thickness during the film growth this boundaries may be eliminated. Films grown on well-oriented substrates show only a few of these defects. In case of increasing Si excess flux during the growth, the TEM investigations, RHEED patterns and damped RHEED-oscillations indicate an abrupt change in the growth process. This is due to the formation of Si islands on the film surface and the SiC island growth by carbonization of these islands. Only/3-SIC was found in this case. 1. Introduction Silicon carbide (SIC) is a material of great technological interest for devices designed to op- erate at high temperatures, high power, high fre- quency and in harsh environments. In particular, * Corresponding author. thin epitaxial films grown on both SiC and Si can be used in semiconductor and optoelectronic de- vices. For device applications, high quality crys- tallinity and interface formation are necessary and, therefore, layer-by-layer growth has to be achieved. Most work concerning the epitaxial growth of SiC films has been done by chemical vapor deposition (CVD) at substrate tempera- tures higher than 1400°C [1-3]. Homoepitaxial 0022-0248/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSDI 0022-0248(95)00170-0