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Title: Special features of the photoluminescence of self-assembled Ge(Si)/Si(001) islands grown on a strained Si{sub 1-x}Ge{sub x} layer

Abstract

The effect of the predeposition of strained Si{sub 1-x}Ge{sub x} layers (x {<=} 20%) on photoluminescence (PL) of self-assembled Ge(Si)/Si(001) islands is studied. A shift of the PL peak related to dome-shaped islands (domes) to lower energies, with respect to the PL peak related to pyramidal islands is observed; this shift is related to a much larger height of the domes compared to that of pyramids. It is found that, as the Ge content in the Si{sub 1-x}Ge{sub x} layer (x) becomes higher than 0.1, two separate peaks appear in the broad PL band related to the islands; these peaks are attributed to the zero-phonon and phonon-assisted optical transitions in the islands. The appearance of these transitions is caused by a change of the TO-phonon type involved in radiative recombination: a TO{sub Ge-Ge} phonon is replaced by a TO{sub Si-Ge} phonon with a shorter wavelength.

Authors:
; ; ; ; ;  [1]
  1. Russian Academy of Sciences, Institute for the Physics of Microstructures (Russian Federation)
Publication Date:
OSTI Identifier:
21088577
Resource Type:
Journal Article
Resource Relation:
Journal Name: Semiconductors; Journal Volume: 40; Journal Issue: 3; Other Information: DOI: 10.1134/S1063782606030158; Copyright (c) 2006 Nauka/Interperiodica; Article Copyright (c) 2006 Pleiades Publishing, Inc; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; GERMANIUM COMPOUNDS; LAYERS; PHOTOLUMINESCENCE; RECOMBINATION; SEMICONDUCTOR MATERIALS; SILICON COMPOUNDS; WAVELENGTHS

Citation Formats

Drozdov, Yu. N., Krasil'nik, Z. F., Lobanov, D. N., E-mail: dima@ipm.sci-nnov.ru, Novikov, A. V., Shaleev, M. V., and Yablonskii, A. N. Special features of the photoluminescence of self-assembled Ge(Si)/Si(001) islands grown on a strained Si{sub 1-x}Ge{sub x} layer. United States: N. p., 2006. Web. doi:10.1134/S1063782606030158.
Drozdov, Yu. N., Krasil'nik, Z. F., Lobanov, D. N., E-mail: dima@ipm.sci-nnov.ru, Novikov, A. V., Shaleev, M. V., & Yablonskii, A. N. Special features of the photoluminescence of self-assembled Ge(Si)/Si(001) islands grown on a strained Si{sub 1-x}Ge{sub x} layer. United States. doi:10.1134/S1063782606030158.
Drozdov, Yu. N., Krasil'nik, Z. F., Lobanov, D. N., E-mail: dima@ipm.sci-nnov.ru, Novikov, A. V., Shaleev, M. V., and Yablonskii, A. N. Wed . "Special features of the photoluminescence of self-assembled Ge(Si)/Si(001) islands grown on a strained Si{sub 1-x}Ge{sub x} layer". United States. doi:10.1134/S1063782606030158.
@article{osti_21088577,
title = {Special features of the photoluminescence of self-assembled Ge(Si)/Si(001) islands grown on a strained Si{sub 1-x}Ge{sub x} layer},
author = {Drozdov, Yu. N. and Krasil'nik, Z. F. and Lobanov, D. N., E-mail: dima@ipm.sci-nnov.ru and Novikov, A. V. and Shaleev, M. V. and Yablonskii, A. N.},
abstractNote = {The effect of the predeposition of strained Si{sub 1-x}Ge{sub x} layers (x {<=} 20%) on photoluminescence (PL) of self-assembled Ge(Si)/Si(001) islands is studied. A shift of the PL peak related to dome-shaped islands (domes) to lower energies, with respect to the PL peak related to pyramidal islands is observed; this shift is related to a much larger height of the domes compared to that of pyramids. It is found that, as the Ge content in the Si{sub 1-x}Ge{sub x} layer (x) becomes higher than 0.1, two separate peaks appear in the broad PL band related to the islands; these peaks are attributed to the zero-phonon and phonon-assisted optical transitions in the islands. The appearance of these transitions is caused by a change of the TO-phonon type involved in radiative recombination: a TO{sub Ge-Ge} phonon is replaced by a TO{sub Si-Ge} phonon with a shorter wavelength.},
doi = {10.1134/S1063782606030158},
journal = {Semiconductors},
number = 3,
volume = 40,
place = {United States},
year = {Wed Mar 15 00:00:00 EST 2006},
month = {Wed Mar 15 00:00:00 EST 2006}
}
  • The results of studying the photoluminescence of the structures with Ge(Si) self-assembled islands embedded into tensile-strained Si layer are reported. The structures were grown on smooth relaxed Si{sub 1-x}Ge{sub x}/Si(001) (x = 0.2-0.3) buffer layers. The photoluminescence peak found in the photoluminescence spectra of the studied structures is related to the indirect (in real space) optical transition between the holes localized in the Ge(Si) islands and electrons localized in the tensile-strained Si layers under and above an island. It is shown that one can efficiently control the position of the photoluminescence peak for a specified type of structure by varyingmore » the thickness of the strained Si layers. It is found that, at 77 K, the intensity of the photoluminescence signal from the heterostructures with Ge(Si) self-assembled islands contained between the tensile-strained Si layers exceeds by an order of magnitude the intensity of the photoluminescence signal from the GeSi structures with islands formed on the Si(001) substrates.« less
  • The effect of the growth temperature (T{sub g}) on photoluminescence of Ge(Si) self-assembled islands embedded between tensile-strained Si layers was studied. The observed redshift of the photoluminescence peak of the dome islands with a decrease of T{sub g} from 700 to 630 deg. C is associated with an increase of Ge content in the islands and with the suppression of smearing of the strained Si layers. The blueshift of the photoluminescence peak with a decrease of T{sub g} from 630 to 600 deg. C is associated with a change of the type of islands on surface, which is accompanied bymore » a decrease in islands' height.« less
  • Atomic-force microscopy, micro-Raman spectroscopy, and high resolution X-ray diffraction are applied to study the spatial ordering in single layers of SiGe nanoislands grown on a strained Si{sub 1-x}Ge{sub x} buffer sublayer. It is shown that, apart from stimulating the spatial ordering of nanoislands, the introduction of a Si{sub 1-x}Ge{sub x} sublayer leads to an enhanced role for interdiffusion processes. An unusually high increase in the volume of nanoislands in the process of the epitaxy is related to the anomalously strong diffusion from the buffer sublayer into the islands that is induced by nonuniform fields of elastic strains. The anisotropy ofmore » the islands shape and spatial ordering is discussed in terms of the anisotropy of the diffusion processes in spatially nonuniform fields of elastic strains.« less
  • B-doped Si{sub 1{minus}{ital x}}Ge{sub {ital x}} layers with Ge fractions, determined by Rutherford backscattering spectroscopy, ranging from 0 to 0.28 and B concentrations, from quantitative secondary-ion spectroscopy measurements, between 5{times}10{sup 16} and 4{times}10{sup 19} cm{sup {minus}3} were grown on Si(001) at temperatures {ital T}{sub {ital s}}=475{endash}575{degree}C by gas-source molecular beam epitaxy from Si{sub 2}H{sub 6}, Ge{sub 2}H{sub 6}, and B{sub 2}H{sub 6}. Film thicknesses ranged from 200 nm for alloys with {ital x}=0.28 to 800 nm with {ital x}=0.05 to 1.4 {mu}m for Si. Structural analyses by high-resolution x-ray diffraction and reciprocal lattice mapping combined with transmission electron microscopy showedmore » that all films were fully strained, with measured relaxations of only {approx_equal}4{times}10{sup {minus}5}, and exhibited no evidence of dislocations or other extended defects. The hole conductivity mobility {mu}{sub {ital c},{ital h}} in these layers increased continuously with increasing Ge concentrations, whereas the Hall mobility decreased yielding a Hall scattering factor that ranged from 0.75 for Si to 0.26 for Si{sub 0.72}Ge{sub 0.28} but was not strongly affected by B concentration. {mu}{sub {ital c},{ital h}}, with {ital C}{sub B}=2{times}10{sup 18} cm{sup {minus}3}, varied from 110 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si{sub 0.95}Ge{sub 0.05} to 158 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si{sub 0.72}Ge{sub 0.28}, compared to 86 cm{sup 2}V{sup {minus}1}s{sup {minus}1} for Si, in good agreement with Boltzmann transport model calculations accounting for changes in the valence-band structure due to the effects of both alloying and biaxial in-plane compressional strain. {copyright} {ital 1996 American Institute of Physics.}« less
  • X-ray diffuse scattering in the vicinity of basis-forbidden Bragg reflections were measured for samples with uncapped self-assembled Ge islands epitaxially grown on Si(001). Our results provide evidence of atomically ordered SiGe domains in both islands and wetting layer. The modeling of x-ray profiles reveals the presence of antiphase boundaries separating the ordered domains in a limited region of the islands. X-ray order parameter results were independently supported by Raman measurements.