Growth of AlN–SiC solid solutions by sequential supply epitaxy

Abstract

Achieving p-type conductivity in the wide-bandgap semiconductors is still a major research challenge. The AlNSiC alloys have the potential for p- and n-type conductivity based on the properties inherited from the easily-to-dope SiC alloy. However, the growth of high quality AlN–SiC alloys was not achieved yet. In this work we propose a new approach for the growth of AlN–SiC alloys by sequential supply epitaxy (SSE) in a low-pressure metalorganic chemical vapor deposition reactor. The alternated supply of trimethyl aluminum and tetraethyl silane during a first sequence followed by the supply of ammonia and ethylene during a second sequence is used to reduce down to almost eliminating the gas-phase reactions. Also, the SSE technique makes it possible to grow the AlN–SiC solid solutions at temperatures rather low, in the range 1200–1300°C. Solid solutions with a rich content of AlN were investigated. The electron spectroscopy for chemical analysis (ESCA) measurements show that SiC is incorporated in AlN and solid solution is actually achieved. The alloy compositions as revealed by ESCA were in agreement with those estimated from X-ray diffraction. The full width at half maximum of the AlN–SiC diffraction peak is in the range 200–300 s. The surface of the epilayers was mirror-like and had a roughness with a RMS value <5 nm.