FEATURES OF OPTICAL TRANSITIONS IN GESISN/SI MULTIPLE QUANTUM WELLS
V.A. Timofeev1, V.I. Mashanov1, A.I. Nikiforov1, I.V. Skvortsov1, I.D. Loshkarev1, D.V. Kolyada2, D.D. Firsov2, O.S. Komkov2
1Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Saint-Petersburg Electrotechnical University "LETI", Saint-Petersburg, Russia
Keywords: molecular beam epitaxy, silicon, germanium, tin, solid solution, multiple quantum wells, band diagram, photoluminescence
Abstract
An interband photoluminescence (PL) of structures with multiple quantum wells (MQWs) with different contents of Ge and Sn has been obtained. The peak position on the PL spectra obtained from Ge0.93-xSixSn0.07/Si MQWs is shifted to longer wavelengths with the Ge content increase in the solid solution and is observed in the energy range of 0,85-0.68 eV for the Ge content from 30 to 78%. Thus, the peak shift over the wavelength from 1,46 μm to 1,82 μm was observed, and the total spectral range of MQWs luminescence covered by these structures was 1,3-2,1 μm. An even more significant shift of the MQWs PL peak to the long wavelength region is achieved by increasing the Sn content. The increase in the Sn content from 7% to 14% at a constant 30% Ge content leads to the peak shift from 0,85 eV to 0,75 eV. A simultaneous increase in the content of both tin and germanium in the solid solution (to 14% and 79%, respectively) makes it possible to obtain the PL peak with the energy of 0,58 eV, which corresponds to the emission wavelength of 2,14 μm. A sharp “red” shift in the position of the PL peak with the temperature increase is found. Its value is up to 50 meV at the change of the heating sample temperature from 11 K to 60-80 K. Such a significant shift in the position of the MQWs PL peak is explained by the model assuming that charge carriers are randomly localized on spatial inhomogeneities of the MQWs at low temperatures, whereas they are redistributed and transferred to a thermodynamically equilibrium state with the lowest energy as the temperature increases.
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