Epitaxial AlN thin films have been grown on 6H-SiC substrates by ultra-high-vacuum (UHV) ion-assisted reactive dc magnetron sputtering. The low-energy ion-assisted growth (E-i = 17-27 eV) results in an increasing surface mobility, promoting domain-boundary annihilation and epitaxial growth. Domain widths increased from 42 to 135 nm and strained-layer epitaxy was observed in this energy range. For E-i> 52 eV, an amorphous interfacial layer of AlN was formed on the SiC, which inhibited epitaxial growth. Using UHV condition and very pure nitrogen sputtering gas yielded reduced impurity levels in the films (O: 3.5 x 10(18) cm(-3)). Analysis techniques used in this study are in situ reflection high-energy electron diffraction, secondary-ion-mass spectroscopy, atomic-force microscopy, x-ray diffraction, and cross-section high-resolution electron microscopy. (C) 2000 American Institute of Physics. [S0003-6951(00)01802-7].

Epitaxial wurzite-structure AIN thin films have been grown on 6H-SiC substrates by ultra-high-vacuum (UHV) low-energy-ion-assisted reactive de magnetron sputtering. The quality of epitaxial AIN films is significantly improved by low-energy ion assistance (E-i = 17-27 eV), during reactive magnetron sputter growth on vicinal (3.5 degrees) 6H-SiC. The ion-assisted growth results in an increased surface mobility, which promotes domain boundary annihilation and epitaxial growth. This results in lateral expansion of column width. Thus, AIN films with domains as large as 40 nm at the interface to 6H-SiC can be realized. At film thickness above 100 nm, the column width expands to 100 nm. The crystal quality of the films is very good with low background impurities (O: 3.5x10 (18)cm(-3)).

Epitaxial aluminum nitride thin films have been grown on silicon carbide (6H-SiC) substrates by pulsed low-energy ion-assisted reactive magnetron sputter deposition (+5/-20 V of bias pulses), with ion-assisted energy (Ei)?22eV, under ultrahigh-vacuum conditions. Surface ion interactions during the negative bias pulse gave rise to enhanced surface mobility of adatoms with beneficial effects, which extended over the limit of ion repelling in the positive pulse as the film thickness increased. High-resolution electron microscopy shows that a large (>90 nm) AlN domain width can form on the substrate. Domain-boundary annihilation and domain suppression during film growth have been observed. The growth rate also increased by a factor of ~4 compared to growth conditions with no ion assistance (Ei=2eV) and by a factor of 2 from dc ion-assisted growth. This indicates that the supply of nitrogen is a limiting factor for AlN formation and that the reactivity of nitrogen is increased on the growing AlN film surface for pulse ion-assisted deposition. High-resolution x-ray diffraction shows a reduction in the full width at half maximum of the rocking curve from 1490 to 1180 arcsec when pulsed ions are used. The cathodoluminescence shows high intensity of near-band edge emissions at wavelengths of 206 (6.02 eV) and 212 nm (5.84 eV) at a measured temperature of 5 K, with relatively low defect and oxygen and carbon impurity related emission, which is indicative of a high quality electronic material. © 2002 American Institute of Physics.

(SiC)(X)(AIN)(1-X) thin films have been grown epitaxially on vicinal 6H-SiC (0001) by low-energy ion assisted dual magnetron sputtering in UHV conditions. AES showed a decreasing Si and C content for an increasing magnetron power ratio, (P-Al/P-SiC). The epitaxial quality of the films was improved as the SiC fraction increased. Films containing less than 5% of Si and C show an evolution of domain width similar to the growth of pure AIN. HRXRD show a decreased c-axis lattice parameter for a film with composition of AINC(X) (0less than or equal toxless than or equal to0.1), indicating carbon substitution in AIN. CL spectra show defect-related peaks of similar to3.87 and similar to4.70 eV, corresponding to O and C impurities respectively as well as on un-identified peak at similar to3.40 eV.