Transmission electron microscopy (TEM) based orientation mapping has been used to measure the length fraction of coherent and incoherent Σ3 grain boundaries in a series of six nanocrystalline Cu thin films with thicknesses in the range of 26–111 nm and grain sizes from 51 to 315 nm. The films were annealed at the same temperature (600 °C) for the same length of time (30 min), have random texture, and vary only in grain size and film thickness. A strong grain size dependence of Σ3 (coherent and incoherent) and coherent Σ3 boundary fraction was observed. The experimental results are quantitatively compared with three physical models for the formation of annealing twins developed for microscale materials. The experimental results for the nanoscale Cu films are found to be in good agreement with the two microscale models that explain twin formation as a growth accident process.

The generation of high frequency steady-state photoconductivity in nitrogen doped hydrogenated amorphous silicon (a-Si:H-N) films has been demonstrated at infrared (IR) frequencies of 650 to 2000 cm-1 or 15 to 5 μm in wavelength. This allows IR photoconductivity to be observed using a simple thermal source. In order to produce high frequency photoconductivity effects the plasma frequency must be increased to the desired device operation frequency or higher as described by the Drude model. IR ellipsometry was used to measure the steady-state permittivity of the a-Si:H-N films as a function of pump illumination intensity. The largest permittivity change was found to be Δεr = 2 resulting from a photo-carrier concentration on the order of 1022 cm-3. IR photoconductivity is shown to be limited by the effective electron mobility at IR frequencies.

We investigated the phase formation sequence in the reaction of multilayer thin films of Nb/Al with overall compositions of 25 and 33 at.% AI. We report novel phenomena which distinguish thin-film reactions unequivocally from those in bulk systems. For sufficiently thin layers composition and stability of product phases are found to deviate significantly from that predicted from the equilibrium phase diagram. We demonstrate that in the Nb/Al system the length scales below which such deviations occur is about 150 nm. We believe that these phenomena occur due to the importance of grain boundary diffusion and hence microstructure in these thin films.