Preparation and optical absorption of InAs nanocrystal-embedded 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 s tudied by a transmission electron microscope. It has been found that with t he increasing substrate temperature, InAs in the matrix undergoes transitio ns 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 o ptical absorption edges of the films was observed from the optical absorpti on spectra. The relationship between the blueshift of optical absorption ed ge and the average size of the nanocrystals has been explained by the effec tive-mass approximation.