Observation of semiconductor to insulator transition in Sb/Sb2O3 clusters synthesized by low-energy cluster beam deposition with different conditions

Nanostructured thin films of Sb2O3 clusters having sizes in the range of 3–17 nm were synthesized by the low-energy cluster beam deposition technique. The crystallite size was found to decrease with increase in rate of flow of the carrier gas. The high-resolution transmission electron microscope image and the selected-area diffraction pattern show the formation of a core shell structure with Sb core and Sb2O3 shell at moderate oxygen flow pressure. Optical absorption spectra exhibit semiconductor characteristics for the samples prepared at intermediate oxygen flow pressure, and insulating features were observed in case of samples prepared at higher oxygen flow pressure. Room-temperature Raman spectra consist of a pair of broad peaks, red shifted with respect to the corresponding peaks of the bulk Sb2O3.