INFLUENCE OF GROWTH-CONDITIONS ON ELECTRICAL CHARACTERISTICS OF ALN ON SIC

Undoped aluminum nitride films were grown on 4H or 6H silicon carbide substrates, using metal-organic chemical-vapor deposition at 1150 degr ees C. Different growth conditions were used, and two different V/III ratios were tested. Metal-insulator-semiconductor capacitors were made for high-frequency capacitance-voltage measurements at room temperatu re, from which the film thickness was determined. Accumulation, deplet ion, deep depletion, and inversion were seen for the best films, which also displayed peaks in x-ray diffraction rocking curves. Although la rge flatband voltage shifts occurred, indicating a fixed charge and in terface trap problem, low conductance was observed. A flow of ammonia during ramp-up was found to improve the AlN films. (C) 1997 American I nstitute of Physics.