Hyperfine interactions at dangling bonds in amorphous germanium

Abstract

Isotope-engineered amorphous germanium (a-Ge͒ films with 73 Ge concentrations in the range of 0.1 to 95.6 % have been investigated by electron spin resonance ͑ESR͒ and electrically detected magnetic resonance ͑EDMR͒ at microwave frequencies between 0.434 and 9.35 GHz. The hyperfine interactions of dangling bond ͑DB͒ defects with many 73 Ge nuclei and their spin localization radius have been extracted from the broadening of the EDMR signals in isotope enriched samples at different 73 Ge concentrations. Linewidths as low as ⌬B pp exp ϭ2.6 G have been observed at 0.434 GHz in a sample without 73 Ge nuclear spins. At low 73 Ge concentrations, the frequency-dependent linewidth B pp SO /ϭ4.4 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 73 Ge atoms on sites close to the DB defect atom are responsible for the overall linewidth. The large linewidth ⌬B pp exp ϭ300 G of samples with 73 Ge concentrations of 95.6% requires a model wave function with a Fermi contact interaction of A iso ϭ29 Gϫg B 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.

Combustion synthesis and characterization of NiO nanoparticles

“…Though there is no apparent change in the positions of XRD peaks, lattice relaxation (expansion) occurs due to the dangling bonds present on the surface of the NiO NPs [27]. Dangling bonds are intrinsic defects present in semiconductors that are responsible for mid gap acceptor and donor levels [39]. The emission characteristics show the origin of four peaks in the photoluminescence spectrum of NiO NPs as visualized in Fig.…”

Weak-magnetism phenomena in heavy-fermion superconductors: selected SR studies

“…The purpose of the present article is to review recent µSR studies on the ground state properties of these latter heavy-fermion compounds, particularly as function of control parameters like chemical substitution and external pressure (see also [16,17,18,19,20]).…”

Spin‐dependent transport in elemental and compound semiconductors and nanostructures

“…Line widths ∆B pp as large as 300 G were found in isotopically pure a- 73 Ge. As a function of the strength of the hyperfine interaction, a critical number of interacting nuclei determines whether a resolved wing structure or a Gaussian line shape is observed, as discussed in [23]. In the case of amorphous Ge, this has been used to extract the hyperfine constants for dangling bonds for the first time.…”