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Rayleigh acoustic mode in superlattice films with layers of a-Si:H and a-SiN(x):H is studied by the application of Brillouin light-scattering technique. Superlattices with different thicknesses of Si:H layers are analyzed, and the phase velocity of the Rayleigh mode is determined. Anomalous properties determined from ultrasonic measurements in superlattices are not observed by using Brillouin light-scattering method.

A time-of-flight secondary ion mass spectrometry is utilized to examine the diffusion mechanisms of fluorine ions in GaN. Strong local confinement and stabilization of fluorine ions in GaN crystal achieved by significant reduction in the number of continuous vacancy chains revealed excellent thermal stability of fluorine ions for device applications.

The molecular dynamic simulation method is used for calculating the potential energies of interstitial and substitutional fluorine ions in AlGaN/GaN material system. It is shown that the fluorine ions are located at the substitutional group-III cation sites S(III) and the diffusion of fluorine ions in implanted III-nitride semiconductors is dominated by S(III)-interstitial process.

The Brillouin light-scattering technique has been exploited for studying the Rayleigh acoustic mode in superlattice films consisting of alternate layers of a-Si:H and a-SiNx:H. The phase velocity of the Rayleigh mode has been measured on superlattices with different thicknesses of the a-Si:H layer. The results obtained have been interpreted in terms of the effective medium model within the elastic continuum approximation; no anomalous behavior is observed, in contrast with previous ultrasonic measurements in superlattice with a minor nitrogen content. [ABSTRACT FROM AUTHOR]