Growth of InAs nanocrystals embedded in SiO₂ films by radio-frequency magnetron cosputtering

In situ radio-frequency (RF) magnetron cosputtering was used to prepare InAs nanocrystals embedded in SiO₂ matrices. The growth behavior of InAs in the composite films has been studied systematically for the first time by transmission electron microscopy. It is found that with increasing substrate temperature, InAs in the matrix undergoes a series of transitions from an initial dispersed phase to a fractal structure, then to nucleation, and finally to grain growth. The average size and the size distribution of the InAs nanocrystals as a function of the RF sputtering parameters were presented and discussed with respect to the crystal growth dynamics. Optical absorption spectra analysis shows that size-controllable InAs nanocrystals embedded in SiO₂ films with a narrow size distribution have been obtained. The blue shift of optical absorption edge versus the average size has been explained by the effective-mass approximation method.