Raman shifts and photoluminescence of the InSb nanocrystals ion beam-synthesized in buried SiO2 layers

The InSb nanocrystals embedded in buried SiO2 layers were obtained by the In+ and Sb+ ion implantation into the SiO2 layers thermally grown on Si wafers followed by the hydrogen transfer of a Si film and high-temperature annealing at 800-1100 °C. Transmission electron microscopy, Raman spectroscopy and photoluminescence were used to study the sample properties. The spherical-shaped InSb nanocrystals distributed close to the implanted atom profiles were obtained in buried SiO2. The InSb TO- and LO-like phonon modes at 187 cm−1 and 195 cm−1 were observed in the Raman spectra. The effect of both phonon quantum confinement and stresses on the phonon frequency shift was calculated. The TO-LO splitting obtained from the ion-beam synthesized InSb nanocrystals was 3 cm−1 less than that from the unstressed bulk monocrystalline InSb. The obtained effect is discussed in the frames of decreasing the transverse effective charge, as well as that of the surface phonon influence. The photoluminescence peak at 1524 nm (0.81 eV) was seen in the low-temperature PL spectra from the samples annealed at 900-1000 °C. Its energy position corresponds to the localized charge carrier energy in the InSb nanocrystals.