Investigation of infrared photoluminescence spectra of Ge_1-x-y Si _x Sn _y /Si nanostructures

Abstract

This work investigates the luminescence properties of pseudomorphic nanostructures with Ge1-x-y Si x Sn y /Si superlattices (SL) grown on silicon substrates by molecular beam epitaxy. It was shown that the addition of Sn (y = 0.07) to the alloy layers within the structures results in a significant shift of the photoluminescence (PL) spectra towards longer wavelengths (2.0-3.5 μm) compared to similar Ge0.7Si0.3/Si superlattices. A series of experiments involving etching the structures to different depths have shown that the observed photoluminescence occurs exactly in the Ge1-x-y Si x Sn y /Si SL region, with the sublinear nature of the PL power dependence indicating the probable participation of defects in radiative recombination. A significant increase in low-temperature PL was observed with a decrease in the thickness of narrow-gap SL layers from 6 to 2 nm, as well as with an increase in the number of superlattice periods from 10 to 30. The obtained structures exhibit relatively good temperature stability of luminescence, which is preserved up to 160 K. Thus, the current work demonstrates the possibility of creating mid-wave IR emitting epitaxial structures on silicon substrates.