We have grown aluminum nitride thin films by ultrahigh vacuum reactive sputter deposition on Si(111) and Si(001) substrates. We show results of film characterization by Raman scattering, ion beam channeling, and transmission electron microscopy, which establish the occurrence of epitaxial growth of wurtzitic aluminum nitride thin films on Si(111) at temperatures above 600 °C. In contrast, microstructural characterization by transmission electron microscopy shows the formation of highly oriented polycrystalline wurtzitic aluminum nitride thin films on Si(001). Real-time substrate curvature measurements reveal the existence of large intrinsic stresses in aluminum nitride thin films grown on both Si(111) and Si(001) substrates.

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Ti-containing and W-containing diamond-like hydrocarbon coatings have been synthesized by glow discharge reactive magnetron sputter deposition in an Ar/CH4 mixture. it is shown that these metal-containing hydrocarbon coatings consist of nanocrystalline TiC and WC embedded in an amorphous hydrocarbon matrix and are thin-film nanocomposite materials. The elastic modulus and hardness of these nanocomposites exhibit systematic dependence on their composition, while the ratio of hardness to modulus remains approximately a constant. It is also shown that the elastic modulus and hardness of these nanocomposites are within macromechanical bounds for two-phase composite materials.

We have studied growth of aluminum nitride (AlN) on Si(111) by ultra-high vacuum (UHV) reactive dc-magnetron sputtering under a mixture of Ar and N2 gases. As-grown films have been examined by x-ray diffraction, Auger electron spectroscopy (AES), and transmission electron microscopy (TEM). Results of x-ray diffraction show texturing with AlN [0001]//Si[111]. Complementary TEM examinations observe epitaxy of AlN on Si(111), with AlN[112̄0]//Si[22̄0]. The AlN/Si interface is sharp and flat. The lowest substrate temperature required to achieve epitaxy Tepi has been determined to be ∼600 °C. A dislocation density in AlN film grown at 700 °C has been estimated to be ∼3×1011/cm2.

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Growth of GaN thin films on AlN-buffered Si(111) by ultrahigh-vacuum rf glow discharge reactive magnetron sputtering is reported. Epitaxy of GaN is established by x-ray and electron diffraction. Raman scattering from the epitaxial films consistent with that of wurtzitic GaN is observed. The ion energies involved in the growth process are quantified by measuring the plasma potentials of the Ar/N2 glow discharge by an emissive Langmuir probe technique. As a function of increasing input power, a systematic increase in ion energies and a systematic straining of the GaN lattice are observed. Measured GaN phonon energy scales with lattice strain.

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