Conditions of growth of high-quality relaxed Si$_{1-x}$Ge$_{x}$ layers with a high Ge content by the vapor-phase decomposition of monogermane on a sublimating Si hot wire

The conditions of the epitaxial growth of high-quality relaxed Si$_{1-x}$Ge$_{x}$ layers by the combined method of the sublimation molecular-beam epitaxy and vapor-phase decomposition of monogermane on a hot wire are considered. The combined growth procedure proposed provides a means for growing Si$_{1-x}$Ge$_{x}$ layers with a thickness of up to 2 $\mu$m and larger. At reduced growth temperatures ($T_{S}\approx$ 325–350$^\circ$C), the procedure allows the growth of Si$_{1-x}$Ge$_{x}$ layers with a small surface roughness (rms $\approx$ 2 nm) and a low density of threading dislocations. The photoluminescence intensity of Si$_{1-x}$Ge$_{x}$ :Er layers is significantly (more than five times) higher than the photoluminescence intensity of layers produced under standard growth conditions ($T_{S}\approx$ 500$^\circ$C) and possess an external quantum efficiency estimated at a level of $\sim$0.4%.