Effect of pressure-enhanced single step annealing on the silicon photoluminescence
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M8.35.1
Effect of pressure-enhanced single step annealing on the silicon photoluminescence S. Binetti (a), A. Le Donne (a), V.V. Emtsev Jr (b), V.V Emtsev(c) and S. Pizzini (a) (a) INFM and Department of Material Science, University of Milano-Bicocca, via Cozzi 53 Milano, Italy (b) Van der Waals – Zeeman Institute Amsterdam University, Valckenierstraat 65 NL-1018 XE Amsterdam, The Netherlands (c) Russian Academy of Sciences, Ioffe Physico-Technical Inst., St Petersburg, RUSSIA
ABSTRACT The effect of single-step annealing under GPa hydrostatic pressures on the photoluminescence of Cz silicon samples has been investigated at 450, 650 and 1000°C. It has been demonstrated that the effect of applied pressure begins to be detectable at 650°C and significant at 1000°C, where not only the effect of the applied pressure but also that of the dopants was clearly evidenced. In the first case the presence of a gap level associated to self-interstitial clusters could be argued, while in the second case both the oxide segregation and the dislocation formation was shown to be enhanced by the pressure and selectively addressed to the type of doping, respectively.
INTRODUCTION We have shown in our earlier works [1,2] that oxygen precipitates emit light in the same range of energy (0.8 eV) where the D1 dislocation emission occurs, showing a close correlation between the light emission and the presence of oxygen segregation at dislocations. Moreover, also the oxygen precipitates emit light at 0.8 eV, showing a unique property, which opens to them the potentiality of being used as localised light sources for room temperatures light emitting devices, in the wavelength range of maximum transmittivity of optical fibers, provided their emissivity could be substantially engineered. As it is well known that the oxygen segregation in CZ silicon is a volume exigent process [3], which should and is effectively affected by an external pressure [4,5], and that the electronic structure of both the oxide nuclei and of the oxygen precipitates should be affected by an external stress, we have systematically studied the effect of the hydrostatic pressure and of the temperature on the photoluminescence (PL) spectra in the infrared (IR) range, in order to understand whether pressure enhanced annealing could improve the light emission processes of both dislocations and precipitates. An indirect result of this work could however be a better knowledge of the effect of pressure on the oxygen nucleation and precipitation processes, as we have already shown that PL spectroscopy is much more sensible than the IR spectroscopy [6,7] and more convenient to be used as the Transmission Electron Microscopy (TEM), when the density of nuclei and precipitates is of the order of 1011 to 1010 cm-3. Eventually, another result of this work would be a better insight about the correlations between oxide nucleation and growth and self-interstitial emission and clustering under an external stress. In fact, as the direct formation of dislocations during the heat treatment at
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