Preparation and optical absorption of InAs nanocrystalembedded thin films

InAs-SiO₂ nanocrystal-embedded films were prepared by using radio-frequency cosputtering. The growth behavior of InAs in the composite film has been studied by a transmission electron microscope. It has been found that with the increasing substrate temperature, InAs in the matrix undergoes transitions from an initial dispersed phase to a fractal structure of the InAs phase, then to nucleation, and finally to grain growth. Large blueshift of the optical absorption edges of the films was observed from the optical absorption spectra. The relationship between the blueshift of optical absorption edge and the average size of the nanocrystals has been explained by the effective-mass approximation.