Phonon spectroscopy of the low energy vibrations of interstitial oxygen in germanium

Abstract

I. Physika1isches lnstitut, Universitiit Stuttgart. W·7rxxl Stuttgart SO, Fed. Rep. of Gennany In oxygen doped germanium we find by phonon spectroscopy with superconducting tunnelling junctions [II (Fig.I) a series of states from 0.18 meV up to 4.08 meV above the ground state (Fig.3). The sequence can be approximated by a free rotation of the interstitial oxygen atom (

Phonon Spectroscopy of Defects Correlated with the Diffusion of Zn into Si

“…On the other hand , the selection rul es for phonon t ransitions may leave levels undetected by phonon spectroscopy. E.g., transitions starting from the supposed thermally occupied, final st ate belonging to As have not been found , in contrast to the case of the first and second excited rotational states of interstitial oxygen in Ge [17]. In any case: it seems clear from the three data sets that there are more than three states belonging to the Zn~ ground st ate, i.e.…”

Interacting quantum rotors in oxygen-doped germanium

“…At low temperatures, those interstitial oxygen atoms are quantum-mechanically delocalized in the annulus around the original bond center of Ge-Ge. [11][12][13] The rotational degree of freedom of oxygen yields low-lying excitations in the far-infrared spectral region, which has been observed in phonon spectroscopy measurements. 11 The energy spectra deduced from these measurements can be accurately reproduced by a quantum rotor model.…”

Theory of Interstitial Oxygen in Silicon and Germanium

“…1. In the case of Ge:O i , the experimental results of Gienger et al [3] are drawn along with the results of our hindered rotor theoretical analysis, where the Hamiltonian of an elastic rotor [10] (H o = Bl 2 − Dl 4 , l being the angular momentum) is perturbed by an angular-dependent potential H ′ = (A/2) cos(6φ) with an amplitude A ≈ 0.6 meV. The model is solved exactly to the required precision, giving a remarkable agreement with experiments, which supports the picture of Fig 1. It has to be stressed, however, that higher harmonics of the angular potential affect very little the displayed results, leaving the hindering potential (and thus the angular energy barrier, and the position and number of minima) indetermined in that respect (the measurement of the splitting of the l = ±6 levels would resolve the indetermination).…”

“…Also displayed is the renormalized potential for the ground state of ν 3 . For Ge:O i , the results of phonon spectroscopy of Gienger et al [3] are compared with the results of the hindered rotor model. Also shown are three potentials compatible with the data, differing in the amplitude of the cos (12φ) term (zero, negative, or positive, respectively).…”

“…It is broadly accepted that interstitial oxygen in silicon (Si:O i ) [1] and in germanium (Ge:O i ) [2][3][4][5] represent very similar centers in their geometry and dynamics. The aim of this paper is to show the contrary: the quantitative differences in the low-energy experimental results for Si:O i [6] and Ge:O i [3] are shown to correspond to fundamentally different realities, that, in turn, lead us to predict substantial differences in their infrared absorption spectra.…”