Search

Transmission Electron Microscopy (TEM) and optical measurements obtained from InN and In1-xGaxN films (0 < x < 0.54) grown by Molecular Beam Epitaxy are presented. Energy gaps measured by absorption, PR, and PL for InN films grown on c-plane Al2O3 were in the range of 0.7 eV. No In or other inclusions were observed in these films, ruling out the possibility of a strong Mie scattering mechanism. In the In1-xGaxN films the relationship between the structural properties and the optical properties, in particular the presence or absence of a Stokes shift between absorption and PL, is discussed. TEM studies show that high quality layers do not have a Stokes shift. Some films had compositional ordering; these films also showed a shift between absorption edge and luminescence peak.s © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present in situ electron diffraction data indicating that Ge nanocrystals embedded in a silica matrix can be solid at temperatures exceeding the bulk Ge melting point. Supercooling is observed when returning from temperatures above the melting point of the Ge nanocrystals. Since melting point hysteresis is observed, it is not clear if nanoclusters are solid or liquid during the initial growth process. Raman spectra of as-grown nanocrystals give a measure of compressive stress and in-situ Raman spectroscopy further confirms the presence of crystalline Ge above 800 °C. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]