Engineering topics

Baidakova, N. A.

Publications and source records attributed to Baidakova, N. A..

5 records

DOE OSTI2019

Comparative Analysis of the Luminescence of Ge:Sb Layers Grown on Ge(001) and Si(001) Substrates

Comparative studies of the luminescence properties of Sb-doped Ge layers grown on Ge(001) and Si(001) substrates are carried out. It is shown that, in contrast to the case of Ge:Sb layers grown on Si, a considerable contribution to the photoluminescence signal from Ge:Sb/Ge(001) layers is made by indirect optical transitions. This fact is attributed to the longer charge-carrier lifetime in Ge:Sb/Ge homoepitaxial structures because of the lack of crystal-lattice defects related to the relaxation of elastic strains in such structures. It is shown that the experimentally observed significant increase in the contribution of direct optical transitions to the total photoluminescence signal with increasing doping level of Ge:Sb/Ge(001) layers results from an increase in the population of electron states in the Γ valley. At Sb concentrations much higher than the equilibrium solubility of Sb in Ge, partial electrical activation of the impurity is observed, and in this case, a profound effect on the emission properties of Ge:Sb layers grown on different substrates is produced by nonradiative-recombination centers, whose role can be played by clusters of impurity atoms.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Enhanced Photoluminescence of Heavily Doped n-Ge/Si(001) Layers

The photoluminescence spectra of epitaxial n{sup +}-Ge:P/Si(001) structures are studied. The structures are grown by hot-wire chemical vapor deposition and doped with phosphorus to the maximum electron concentration 1 × 10{sup 20} cm{sup –3} from a source based on thermally decomposed GaP. The effects of the doping level and rapid thermal annealing of n{sup +}-Ge:P layers on the photoluminescence spectra are studied. It is demonstrated that the epitaxial n{sup +}-Ge:P/Si(001) layers grown by hot-wire chemical vapor deposition are promising for application as active regions of light-emitting optoelectronic devices operating in the near-infrared spectral region.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2019

Influence of Annealing on the Properties of Ge:Sb/Si(001) Layers with an Antimony Concentration Above Its Equilibrium Solubility in Germanium

The influence of rapid thermal annealing on the electrical and radiative properties of Ge:Sb/Si(001) epitaxial layers with an antimony concentration substantially higher than its equilibrium solubility in germanium is investigated. Local variations in the electrical and luminescence properties of n-Ge/Si(001) throughout the structure depth are investigated by means of the precise chemical etching of Ge. It is shown that a variation in the properties of such layers at relatively low (≤500°C) annealing temperatures (decrease in the electron concentration and photoluminescence intensity) occur in the absence of the noticeable diffusion-related redistribution of dopant atoms. Variations in the electrical and luminescence properties of Ge:Sb layers at relatively high (≥700°C) annealing temperatures are caused by the substantial redistribution of Sb due to its bulk diffusion and desorption from the surface. In particular, Sb diffusion leads to the formation of doped layers in initially undoped parts of the studied structures, which start to give a substantial contribution to the resulting conductivity of the structure and its photoluminescence signal.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

DOE OSTI2018

Formation and Properties of Locally Tensile Strained Ge Microstructures for Silicon Photonics

The formation and properties of locally tensile strained Ge microstructures (“microbridges”) based on Ge layers grown on silicon substrates are investigated. The elastic-strain distribution in suspended Ge microbridges is analyzed theoretically. This analysis indicates that, in order to attain the maximum tensile strain within a microbridge, the accumulation of strain in all corners of the fabricated microstructure has to be minimized. Measurements of the local strain using Raman scattering show significant enhancement of the tensile strain from 0.2–0.25% in the initial Ge film to ~2.4% in the Ge microbridges. A considerable increase in the luminescence intensity and significant modification of its spectrum in the regions of maximum tensile strain in Ge microbridges and in their vicinity as compared to weakly strained regions of the initial Ge film is demonstrated by microphotoluminescence spectroscopy.

36 MATERIALS SCIENCE↗

DOE OSTI2016

Strained multilayer structures with pseudomorphic GeSiSn layers

The temperature and composition dependences of the critical thickness of the 2D–3D transition for a GeSiSn film on Si(100) have been studied. The regularities of the formation of multilayer structures with pseudomorphic GeSiSn layers directly on a Si substrate, without relaxed buffer layers, were investigated for the first time. The possibility of forming multilayer structures based on pseudomorphic GeSiSn layers has been shown and the lattice parameters have been determined using transmission electron microscopy. The grown structures demonstrate photoluminescence for Sn contents from 3.5 to 5% in GeSiSn layers.

36 MATERIALS SCIENCE↗