Temperature Dependence of Raman Scattering in ZnO
Abstract
We present a Raman scattering study of wurtzite ZnO over a temperature range from 80 to 750 K. Second order Raman features are interpreted in the light of recent ab initio phonon density of states calculations. The temperature dependence of the Raman intensities allows the assignment of difference modes to be made unambiguously. Some weak, sharp Raman peaks are detected whose temperature dependence suggests they may be due to impurity modes. High-resolution spectra of the E2 high, A1(LO), and E1(LO) modes were recorded, and an analysis of the anharmonicity and lifetimes of these phonons is carried out. The E2 high mode displays a visibly asymmetric line shape. This can be attributed to anharmonic interaction with transverse and longitudinal acoustic phonon combinations in the vicinity of the K point, where the two-phonon density of states displays a sharp edge around the E2 high frequency. The temperature dependence of the linewidth and frequency of the E2 high mode is well described by a perturbation-theory renormalization of the harmonic E2 high frequency resulting from the interaction with the acoustic two-phonon density of states. In contrast, the A1(LO) and E1(LO) frequencies lie in a region of nearly flat two-phonon density of states, and they exhibit a nearly symmetric Lorentzian line shape with a temperature dependence that is well accounted for by a dominating asymmetric decay channel.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 06, 2007
- Accession Number
- ADA485744
Entities
People
- Buguo Wang
- Esther Alarcon-llado
- Jordi Ibanez
- Juan Jimenez
- L. Artús
- Michael J. Callahan
- Ramon Cuscó
Organizations
- Air Force Research Laboratory