Comparison of the microstructure and chemistry of GaN(0001) films grown using trimethylgallium and triethylgallium on AlN/SiC substrates

The metalorganic chemical vapor deposition of GaN(0001) films using triethylgallium (TEG) and trimethylgallium (TMG) precursors on AlN/6H-SiC(0001) substrates has been conducted using various sets of two temperatures, and the microstructural and chemical differences in the films determined. Growth of films at 980 degrees C and 1020 degrees C using TEG and TMG, respectively, resulted in the formation of separate elongated islands. Growth at the optimum temperatures (for our system) of 1020 degrees C and 1050 degrees C using these two respective precursors resulted in smooth surface microstructures. Analogous depositions at 1050 degrees C and 1080 degrees C resulted in the formation of hillocks over most of the surfaces. In the GaN films grown using TEG at 1020 degrees C the concentrations of carbon (3x10(17) cm(-3)) and hydrogen (1x10(18) cm(-3)) were similar to 10 times and similar to 2 times lower than in the films deposited using TMG at 1050 degrees C. The concentrations of oxygen and silicon were 1x10(17) cm(-3) in the films grown using either precursor. Atomic force microscopy of the films grown using TEG and TMG at 1020 degrees C and 1050 degrees C, respectively, revealed a similar surface roughness with rms values of similar to 1.8 nm within 50 mu m x 50 mu m scans. The full width at half maxima determined from omega scans of the GaN(0002) peak were similar to 250 arcsec for films grown using both precursors. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.