A. K. Gutakovskii

Publications (3)1.88 Total impact

• Article: Effect of quantum confinement on optical properties of Ge nanocrystals in GeO2 films

  E. B. Gorokhov, V. A. Volodin, D. V. Marin, D. A. Orekhov, A. G. Cherkov, A. K. Gutakovskii, V. A. Shvets, A. G. Borisov, M. D. Efremov
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  ABSTRACT: Germanium dioxide films containing Ge nanocrystals are studied. The films have been prepared by two methods: (i) deposition from supersaturated GeO vapors with subsequent decomposition of metastable germanium monoxide into a heterophase Ge:GeO2 system, and (ii) formation of anomalously thick native germanium oxides with a GeO2(H2O) chemical composition by a catalyst-accelerated oxidation of germanium. The films, which have been prepared on various substrates, are studied using the photoluminescence technique, Raman spectroscopy, spectral ellipsometry, and high-resolution electron microscopy. In the GeO2 films with built-in Ge nanoclusters, intense photoluminescence is detected at room temperature. The nanocluster sizes are estimated from the position of the Raman peak related to localized optical phonons. The correlation between a decrease in the nanocluster size and the shift of the photoluminescence peaks to the blue spectral region as the relative Ge content decreases is revealed. The presence of nanoclusters is confirmed by the data obtained from high-resolution electron microscopy. The correlation of the optical gap calculated taking into account the quantum confinement of electrons and holes in the nanoclusters with the experimentally observed luminescence peak is established. It can be concluded from the data obtained that the Ge nanoclusters constructed in the GeO2 matrix represent type I quantum dots.
  Semiconductors 09/2005; 39(10):1168-1175. · 0.63 Impact Factor
• Article: The formation of silicon nanocrystals in SiO2 layers by the implantation of Si ions with intermediate heat treatments

  G. A. Kachurin, V. A. Volodin, D. I. Tetel’baum, D. V. Marin, A. F. Leier, A. K. Gutakovskii, A. G. Cherkov, A. N. Mikhailov
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  ABSTRACT: The effect of heat treatments at 1100°C on an ion-beam synthesis of Si nanocrystals in SiO2 layers is studied. The ion-implanted samples are subjected either to a single heat treatment after the total ion dose (1017 cm−2 has been implanted, two heat treatments (a heat treatment after the ion implantation of each half of the total dose), or three heat treatments (a heat treatment after each third of the dose). The total duration of the heat treatments is maintained at 2 h. It is found that the intermediate heat treatments lead to a shift of the Raman spectrum of the nanocrystals to longer wavelengths and to a shift of the photoluminescence spectrum to shorter wavelengths. Study using electron microscopy shows that the size of the nanoprecipitates decreases, which is accompanied by the disappearance of the characteristic features of crystallinity; however, the features of photoluminescence remain characteristic of the nanocrystals. The experimental data obtained are accounted for by a preferential drain of Si atoms to newly formed clusters, which is consistent with the results of a corresponding numerical simulation. It is believed that small nanocrystals make the main contribution to photoluminescence, whereas the Raman scattering and electron microscopy are more sensitive to larger nanocrystals.
  Semiconductors 04/2005; 39(5):552-556. · 0.63 Impact Factor
• Article: Effect of ion dose and annealing mode on photoluminescence from SiO2 implanted with Si ions

  G. A. Kachurin, A. F. Leier, K. S. Zhuravlev, I. E. Tyschenko, A. K. Gutakovskii, V. A. Volodin, W. Skorupa, R. A. Yankov
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  ABSTRACT: This paper discusses the photoluminescence spectra of 500-nm-thick layers of SiO2 implanted with Si ions at doses of 1.6×1016, 4×1016, and 1.6×1017 cm−2 and then annealed in the steady-state region (30 min) and pulsed regime (1 s and 20 ms). Structural changes were monitored by high-resolution electron microscopy and Raman scattering. It was found that when the ion dose was decreased from 4×1016 cm−2 to 1.6×1016 cm−2, generation of centers that luminesce weakly in the visible ceased. Moreover, subsequent anneals no longer led to the formation of silicon nanocrystallites or centers that luminesce strongly in the infrared. Annealing after heavy ion doses affected the photoluminescence spectrum in the following ways, depending on the anneal temperature: growth (up to ∼700 °C), quenching (at 800–900 °C), and the appearance of a very intense photoluminescence band near 820 nm (at >900 °C). The last stage corresponds to the appearance of Si nanocrystallites. The dose dependence is explained by a loss of stability brought on by segregation of Si from SiO2 and interactions between the excess Si atoms, which form percolation clusters. At low heating levels, the distinctive features of the anneals originate predominantly with the percolation Si clusters; above ∼700 °C these clusters are converted into amorphous Si-phase nanoprecipitates, which emit no photoluminescence. At temperatures above 900 °C the Si nanocrystallites that form emit in a strong luminescence band because of the quantum-well effect. The difference between the rates of percolation and conversion of the clusters into nanoprecipitates allows the precipitation of Si to be controlled by combinations of these annealings.
  Semiconductors 01/1998; 32(11):1222-1228. · 0.63 Impact Factor