Composition modulation in In_xGa_1-xAs nanocrystals embedded in SiO₂ film by radio frequency magnetron cosputtering

We have succeeded in preparing In_xGa_1-xAs (0.2≤x≤0.8) nanocrystals with 3-5 nm in size embedded in SiO₂ thin film by using the radio frequency magnetron cosputtering technique. The analyses of x-ray diffraction and Raman spectra strongly suggest the existence of In_xGa_1-xAs nanocrystals in the matrices. It has been found that the optical absorption edge, lattice constant and Raman shift can be modulated by composition of In_xGa_1-xAs by varying the effectively sputtered area ratio of InAs to GaAs on the target. The blueshift of the optical absorption edge is explained by the effective mass approximation method.