Hyperfine interactions at dangling bonds in amorphous germanium

T. Graf, T. Ishikawa, Kohei M Itoh, E. E. Haller, M. Stutzmann, M. S. Brandt

Research output: Contribution to journalArticle

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Abstract

Isotope-engineered amorphous germanium (a-Ge) films with 73Ge concentrations in the range of 0.1 to 95.6% have been investigated by electron spin resonance (ESR) and electrically detected magnetic resonance (EDMR) at microwave frequencies between 0.434 and 9.35 GHz. The hyperfine interactions of dangling bond (DB) defects with many 73Ge nuclei and their spin localization radius have been extracted from the broadening of the EDMR signals in isotope enriched samples at different 73Ge concentrations. Linewidths as low as ΔBpp exp = 2.6 G have been observed at 0.434 GHz in a sample without 73Ge nuclear spins. At low 73Ge concentrations, the frequency-dependent linewidth B pp SO = 4.4 G/GHz is determined by g-factor anisotropy and disorder. A frequency-independent linewidth contribution of about 1 G is attributed to dipolar broadening between the DB electronic spins. Over a large range of intermediate concentrations, the statistically distributed nuclear spins of 73Ge atoms on sites close to the DB defect atom are responsible for the overall linewidth. The large linewidth Δ pp exp = 300 G of samples with 73Ge concentrations of 95.6% requires a model wave function with a Fermi contact interaction of Aiso = 29 Gx μB at the defect atom, indicating that a fraction of 3.4% of the DB wave function originates from s-like orbitals there. The decay of the rest of the DB wave function can be described with a spin localization radius of 3.5 Å by a numerical model for the statistical hyperfine broadening. The delocalization of the DB spin is much smaller than that of the DB charge density determined in transport measurements.

Original languageEnglish
Article number205208
Pages (from-to)2052081-20520816
Number of pages18468736
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume68
Issue number20
Publication statusPublished - 2003 Nov

Fingerprint

Germanium
Dangling bonds
germanium
Linewidth
wave functions
nuclear spin
Wave functions
magnetic resonance
defects
isotopes
interactions
atoms
Magnetic resonance
radii
Isotopes
Atoms
Defects
microwave frequencies
low concentrations
electric contacts

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Graf, T., Ishikawa, T., Itoh, K. M., Haller, E. E., Stutzmann, M., & Brandt, M. S. (2003). Hyperfine interactions at dangling bonds in amorphous germanium. Physical Review B - Condensed Matter and Materials Physics, 68(20), 2052081-20520816. [205208].

Hyperfine interactions at dangling bonds in amorphous germanium. / Graf, T.; Ishikawa, T.; Itoh, Kohei M; Haller, E. E.; Stutzmann, M.; Brandt, M. S.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 68, No. 20, 205208, 11.2003, p. 2052081-20520816.

Research output: Contribution to journalArticle

Graf, T, Ishikawa, T, Itoh, KM, Haller, EE, Stutzmann, M & Brandt, MS 2003, 'Hyperfine interactions at dangling bonds in amorphous germanium', Physical Review B - Condensed Matter and Materials Physics, vol. 68, no. 20, 205208, pp. 2052081-20520816.
Graf T, Ishikawa T, Itoh KM, Haller EE, Stutzmann M, Brandt MS. Hyperfine interactions at dangling bonds in amorphous germanium. Physical Review B - Condensed Matter and Materials Physics. 2003 Nov;68(20):2052081-20520816. 205208.
Graf, T. ; Ishikawa, T. ; Itoh, Kohei M ; Haller, E. E. ; Stutzmann, M. ; Brandt, M. S. / Hyperfine interactions at dangling bonds in amorphous germanium. In: Physical Review B - Condensed Matter and Materials Physics. 2003 ; Vol. 68, No. 20. pp. 2052081-20520816.
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