Temperature dependence of the vibrational spectrum of a Li-OH complex in ZnO: Infrared absorption experiments and theory

Abstract

Considerable interest has developed in the potential use of II-VI oxides as electronic and optical materials. In several cases, alkali atoms have been suggested as dopants. We report on the theoretical and experimental investigation of infrared and vibrational properties of a Li-OH complex in ZnO. Earlier infrared experiments revealed a broad OH-like band centered at 3577.3 cm −1 ͑12 K͒, with full width at half maximum ranging from 0.4 cm −1 ͑12 K͒ to 41.3 cm −1 ͑300 K͒ and a corresponding shift in peak position to 3547 cm −1 , suggesting a significant coupling of the OH stretch with other modes. We have performed similar experiments on the OD version of this defect and have theoretically investigated the coupling of these stretch modes to other modes. The lack of a significant isotope dependence of the resulting parameters suggests that the defect couples to the host, rather than to large-amplitude motion of the H or D itself.

Identification of hydrogen defects linked to boron substitution in synthetic forsterite and natural olivine

“…Although not fully understood, the stronger temperature dependence of the B-related band probably stems from anharmonic coupling to a low-frequency vibration mode . This further confirms the importance of the local geometry of the defect in the control of anharmonic vibrational properties (Martin et al 2006). The B_H_2 configuration is less stable by 26.5 kJ/mol, leading to a theoretical B_H_2/B_H_1 abundance ratio of ∼12.7%.…”

Interplay between interstitial and substitutional hydrogen donors in ZnO

“…4(b) matches the LVM frequency of H BC reasonably well over the whole temperature range. Within the error bars, the observed exchange mode E 0 is slightly below the values determined from the hydrogen motion in the Li-OH and CuH 2 complexes [37,42].…”

“…Harris et al [34] and Persson and Ryberg [35] consider an interaction with a single low-energy phonon. Lüpke et al [36] and Martin et al [37] developed a theory for more than one exchange mode. The involvement of other LVMs into the dephasing process was considered by West and Estreicher [38].…”

“…(1) and accounts for the deviation from the values reported in Refs. [37,42]. Note that the linewidth in the case of Fano resonance is a combined effect of the "friction" with the lattice as well as the interaction with the electron continuum, which prevented us from a more detailed analysis of .…”

Theoretical Raman spectrum and anharmonicity of tetrahedral OH defects in hydrous forsterite

“…Infrared absorption corresponds to a coherent excitation of an ensemble of oscillators. Accordingly, the decay of the excited state can occur either through energy transfer from individual excited states to other vibrational states of the crystal (population relaxation process) or through thermal fluctuations inducing a loss in the phase coherence of the excited state (vibrational phase relaxation) (Bonn et al, 1996;Budde et al, 2001;Martin et al 2006). For high-energy OH stretching modes, population relaxation is not an efficient process because energy conservation requires a coupling with a large number of the host vibrational states.…”