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Title: Vacancy-impurity pairs in relaxed Si{sub 1-x}Ge{sub x} layers studied by positron annihilation spectroscopy

Abstract

Positron annihilation spectroscopy was applied to study relaxed P-doped n-type and undoped Si{sub 1-x}Ge{sub x} layers with x up to 0.30. The as-grown SiGe layers were found to be defect free and annihilation parameters in a random SiGe alloy could be represented as superpositions of annihilations in bulk Si and Ge. A 2 MeV proton irradiation with a 1.6x10{sup 15} cm{sup -2} fluence was used to produce saturated positron trapping in monovacancy related defects in the n-type layers. The defects were identified as V-P pairs, the E center. The distribution of Si and Ge atoms surrounding the E center was the same as in the host lattice. The process leading to the formation of V-P pairs therefore does not seem to have a significant preference for either Si or Ge atoms. In undoped Si{sub 1-x}Ge{sub x} we find that a similar irradiation produces a low concentration of divacancies or larger vacancy defects and found no evidence of monovacancies surrounded by several Ge atoms.

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. Laboratory of Physics, Helsinki University of Technology, P.O.Box 1100 FIN-02015 HUT (Finland)
  2. (Sweden)
  3. (Norway)
Publication Date:
OSTI Identifier:
20788080
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. B, Condensed Matter and Materials Physics; Journal Volume: 73; Journal Issue: 16; Other Information: DOI: 10.1103/PhysRevB.73.165209; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNIHILATION; ATOMS; CRYSTALS; DOPED MATERIALS; E CENTERS; GERMANIUM ALLOYS; GERMANIUM SILICIDES; IMPURITIES; IRRADIATION; LAYERS; MEV RANGE; PHOSPHORUS; PHYSICAL RADIATION EFFECTS; POSITRONS; PROTONS; SEMICONDUCTOR MATERIALS; SILICON ALLOYS; SPECTROSCOPY; THIN FILMS; TRAPPING

Citation Formats

Rummukainen, M., Slotte, J., Saarinen, K., Radamson, H. H., Haallstedt, J., Kuznetsov, A. Yu., School of Information and Communication Technology, Kungliga Tekniska Hoegskolan, Isafjordsgatan 22 V 26, Electrum 229, 16440 Kista, and Department of Physics, Oslo University, Physical Electronics, P.B. 1048, Blindern N-0316 Oslo. Vacancy-impurity pairs in relaxed Si{sub 1-x}Ge{sub x} layers studied by positron annihilation spectroscopy. United States: N. p., 2006. Web. doi:10.1103/PHYSREVB.73.1.
Rummukainen, M., Slotte, J., Saarinen, K., Radamson, H. H., Haallstedt, J., Kuznetsov, A. Yu., School of Information and Communication Technology, Kungliga Tekniska Hoegskolan, Isafjordsgatan 22 V 26, Electrum 229, 16440 Kista, & Department of Physics, Oslo University, Physical Electronics, P.B. 1048, Blindern N-0316 Oslo. Vacancy-impurity pairs in relaxed Si{sub 1-x}Ge{sub x} layers studied by positron annihilation spectroscopy. United States. doi:10.1103/PHYSREVB.73.1.
Rummukainen, M., Slotte, J., Saarinen, K., Radamson, H. H., Haallstedt, J., Kuznetsov, A. Yu., School of Information and Communication Technology, Kungliga Tekniska Hoegskolan, Isafjordsgatan 22 V 26, Electrum 229, 16440 Kista, and Department of Physics, Oslo University, Physical Electronics, P.B. 1048, Blindern N-0316 Oslo. Sat . "Vacancy-impurity pairs in relaxed Si{sub 1-x}Ge{sub x} layers studied by positron annihilation spectroscopy". United States. doi:10.1103/PHYSREVB.73.1.
@article{osti_20788080,
title = {Vacancy-impurity pairs in relaxed Si{sub 1-x}Ge{sub x} layers studied by positron annihilation spectroscopy},
author = {Rummukainen, M. and Slotte, J. and Saarinen, K. and Radamson, H. H. and Haallstedt, J. and Kuznetsov, A. Yu. and School of Information and Communication Technology, Kungliga Tekniska Hoegskolan, Isafjordsgatan 22 V 26, Electrum 229, 16440 Kista and Department of Physics, Oslo University, Physical Electronics, P.B. 1048, Blindern N-0316 Oslo},
abstractNote = {Positron annihilation spectroscopy was applied to study relaxed P-doped n-type and undoped Si{sub 1-x}Ge{sub x} layers with x up to 0.30. The as-grown SiGe layers were found to be defect free and annihilation parameters in a random SiGe alloy could be represented as superpositions of annihilations in bulk Si and Ge. A 2 MeV proton irradiation with a 1.6x10{sup 15} cm{sup -2} fluence was used to produce saturated positron trapping in monovacancy related defects in the n-type layers. The defects were identified as V-P pairs, the E center. The distribution of Si and Ge atoms surrounding the E center was the same as in the host lattice. The process leading to the formation of V-P pairs therefore does not seem to have a significant preference for either Si or Ge atoms. In undoped Si{sub 1-x}Ge{sub x} we find that a similar irradiation produces a low concentration of divacancies or larger vacancy defects and found no evidence of monovacancies surrounded by several Ge atoms.},
doi = {10.1103/PHYSREVB.73.1},
journal = {Physical Review. B, Condensed Matter and Materials Physics},
number = 16,
volume = 73,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • The conditions of the epitaxial growth of high-quality relaxed Si{sub 1–x}Ge{sub 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{sub 1–x}Ge{sub x} layers with a thickness of up to 2 µm and larger. At reduced growth temperatures (T{sub S} = 325–350°C), the procedure allows the growth of Si{sub 1–x}Ge{sub x} layers with a small surface roughness (rms ≈ 2 nm) and a low density of threading dislocations. The photoluminescence intensity of Si{sub 1–x}Ge{sub x}:Er layers ismore » significantly (more than five times) higher than the photoluminescence intensity of layers produced under standard growth conditions (T{sub S} ≈ 500°C) and possess an external quantum efficiency estimated at a level of ~0.4%.« less
  • The strain dependence of Si-Ge interdiffusion in epitaxial Si/Si{sub 1-y}Ge{sub y}/Si heterostructures on relaxed Si{sub 1-x}Ge{sub x} substrates has been studied using secondary ion mass spectrometry, Raman spectroscopy, and simulations. At 800 and 880 deg. C, significantly enhanced Si-Ge interdiffusion is observed in Si/Si{sub 1-y}Ge{sub y}/Si heterostructures (y=0.56, 0.45, and 0.3) with Si{sub 1-y}Ge{sub y} layers under compressive strain of -1%, compared to those under no strain. In contrast, tensile strain of 1% in Si{sub 0.70}Ge{sub 0.30} layer has no observable effect on interdiffusion in Si/Si{sub 0.70}Ge{sub 0.30}/Si heterostructures. These results are relevant to the device and process design ofmore » high mobility dual channel and heterostructure-on-insulator metal oxide semiconductor field effect transistors.« less
  • Proton-irradiation-induced electronic defects in relaxed, epitaxial p-type Si{sub 1{minus}x}Ge{sub x} layers grown by molecular-beam epitaxy have been investigated by deep level transient spectroscopy (DLTS) for 0{le}x{le}0.25. Three dominating lines in the DLTS spectra have been observed and correlated to the divacancy, interstitial carbon, and the interstitial-boron{endash}substitutional-carbon pair. For all three levels the activation enthalpy relative to the valence band decreases with increasing Ge content. Annealing studies demonstrated that the annealing of the defect level, identified as interstitial carbon, is retarded with increasing Ge content, while the annealing temperatures of the two other defects are similar to those observed in silicon.more » {copyright} {ital 1997 American Institute of Physics.}« less
  • Ge{sub 0.94}Sn{sub 0.06} films with high tensile strain were grown on strain-relaxed In{sub y}Ga{sub 1−y}P virtual substrates using solid-source molecular beam epitaxy. The in-plane tensile strain in the Ge{sub 0.94}Sn{sub 0.06} film was varied by changing the In mole fraction in In{sub x}Ga{sub 1−x}P buffer layer. The tensile strained Ge{sub 0.94}Sn{sub 0.06} films were investigated by transmission electron microscopy, x-ray diffraction, and Raman spectroscopy. An in-plane tensile strain of up to 1% in the Ge{sub 0.94}Sn{sub 0.06} was measured, which is much higher than that achieved using other buffer systems. Controlled thermal anneal experiment demonstrated that the strain was notmore » relaxed for temperatures up to 500 °C. The band alignment of the tensile strained Ge{sub 0.94}Sn{sub 0.06} on In{sub 0.77}Ga{sub 0.23}P was obtained by high resolution x-ray photoelectron spectroscopy. The Ge{sub 0.94}Sn{sub 0.06}/In{sub 0.77}Ga{sub 0.23}P interface was found to be of the type I band alignment, with a valence band offset of 0.31 ± 0.12 eV and a conduction band offset of 0.74 ± 0.12 eV.« less
  • Using spectroscopic ellipsometry, we measured the pseudodielectric function of Si{sub 1{minus}{ital x}{minus}{ital y}}Ge{sub {ital x}}C{sub {ital y}} alloys (0{le}{ital x}{le}0.48,0{le}{ital y}{le}0.05) grown on Si(001) using molecular beam epitaxy. For pseudomorphically strained layers, the energy shifts of the {ital E}{sub 1}, {ital E}{sub 1}+{Delta}{sub 1}, {ital E}{sub 0}{sup {prime}}, and {ital E}{sub 2} transitions are determined by line shape analysis and are due to alloy composition effects, as well as hydrostatic and shear strain. We developed expressions for hydrostatic and shear shift from continuum elasticity theory, using deformation potentials for Si and Ge, for biaxial stress parallel to the (001) growthmore » plane in a diamond or zinc blende-type crystal and applied this to the ternary Si{endash}Ge{endash}C alloy. The energies of {ital E}{sub 1} and its spin-orbit split partner {ital E}{sub 1}+{Delta}{sub 1} agree fairly well with theory. The {ital E}{sub 2} transitions in Si{sub 1{minus}{ital x}}Ge{sub {ital x}} at around 4.3 eV depend linearly on Ge concentration. In case of relaxed layers, the {ital E}{sub 1} and {ital E}{sub 1}+{Delta}{sub 1} transitions are inhomogeneously broadened due to the influence of misfit and threading dislocations. For a silicon cap on top of a dislocated, relaxed SiGe layer, we recovered the bulk Si dielectric function. {copyright} {ital 1996 American Institute of Physics.}« less