Abstract
The dependences of the two-dimensional to three-dimensional growth (2D-3D) critical transition thickness on the composition for GeSiSn films with a fixed Ge content and Sn content from 0 to 16% at the growth temperature of 150 °С have been obtained. The phase diagrams of the superstructure change during the epitaxial growth of Sn on Si and on Ge(100) have been built. Using the phase diagram data, it becomes possible to identify the Sn cover on the Si surface and to control the Sn segregation on the superstructure observed on the reflection high-energy electron diffraction (RHEED) pattern. The multilayer structures with the GeSiSn pseudomorphic layers and island array of a density up to 1.8 × 1012 cm−2 have been grown with the considering of the Sn segregation suppression by the decrease of GeSiSn and Si growth temperature. The double-domain (10 × 1) superstructure related to the presence of Sn on the surface was first observed in the multilayer periodic structures during Si growth on the GeSiSn layer. The periodical GeSiSn/Si structures demonstrated the photoluminescence in the range of 0.6–0.85 eV corresponding to the wavelength range of 1.45–2 μm. The calculation of the band diagram for the structure with the pseudomorphic Ge0.315Si0.65Sn0.035 layers allows assuming that photoluminescence peaks correspond to the interband transitions between the X valley in Si or the Δ4-valley in GeSiSn and the subband of heavy holes in the GeSiSn layer.
Highlights
The effective light-emitting devices were not presented since Si is the semiconductor with the indirect bandgap, the silicon photonics devices, such as waveguides [1], photodetectors [2], and modulators [3] were successfully created.The Sn addition in the matrix of Ge, Si, or GeSi solid solution is one of the approaches for obtaining the direct bandgap semiconductor which is based on the IV group materials
The purpose of this paper is to study the elastically stressed pseudomorphic GeSiSn film growth, threedimensional nanoisland formation and to obtain the multilayer periodical structures containing pseudomorphic GeSiSn layers and nanoislands
The optical properties of multilayer periodic structures with GeSiSn layers were investigated by photoluminescence for structures with different Sn contents. The structures demonstrated their photoluminescence in the range of 0.6–0.8 eV, which corresponds to the wavelength range of 1.45–2 μm (Fig. 7)
Summary
The Sn addition in the matrix of Ge, Si, or GeSi solid solution is one of the approaches for obtaining the direct bandgap semiconductor which is based on the IV group materials. The inclusion of Sn in the Ge lattice reduces the difference between the minima of Г and L valleys, and GeSn can become a direct bandgap material. As it was shown, the directness for the GeSn cubic lattice. One of the serious problems is the Sn inclusion (precipitates) formation during GeSn layer growth [10, 11]. Sn segregation is observed in the process
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