Quantum confinement in InSb microcrystallites embedded in SiO₂ thin films

Semiconductor InSb microcrystallites were embedded in SiO₂ thin films by rf cosputtering technique. Structures of the thin films were characterized by transmission electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Average size of the microcrystallites, depending on post-annealing temperature and time, is on the order of magnitude of nanometer. Absorption spectra of the films were measured and large blue shifts of absorption edge were observed in a wide range from 300 to 1500 nm. The blue shifts were attributed to the quantum confinement effect and explained in the model of effective-mass approximation.