Multimode phonon structure of Be-containing II - VI mixed crystals determined by IR spectroscopic ellipsometry
✍ Scribed by A. A. Wronkowska; A. Wronkowski; Ł. Skowroński; F. Firszt
- Publisher
- John Wiley and Sons
- Year
- 2010
- Tongue
- English
- Weight
- 292 KB
- Volume
- 45
- Category
- Article
- ISSN
- 0232-1300
No coin nor oath required. For personal study only.
✦ Synopsis
Spectroscopic ellipsometry in the infrared spectral range 250-5000 cm -1 is used for analysis of the dielectric response of Zn 1-x-y Be x Mg y Se and Zn 1-x-y Be x Mn y Se crystals grown by a high-pressure Bridgman method. Ellipsometric spectra display features in the spectral range 390-500 cm -1 associated with BeSe-type phonon modes. In the optical spectra of Zn 1-x-y Be x Mg y Se crystals both BeSe-type and MgSe-type lattice absorption bands are detected. The MgSe-like modes are located at approximately 300 cm -1 . The complex dielectric functions can be reproduced using a model with two or three and one or two classical damped oscillators corresponding to the BeSe-like and the MgSe-like transverse-optical phonon modes, respectively. The frequencies of longitudinal-optical phonons have been derived from the dielectric loss functions. A red-shift of the BeSe-like phonons frequencies with a mean rate 0.42 cm -1 (0.50 cm -1 ) per mole percent of Mg (Mn) incorporated to the alloy has been found for examined concentration range x, y ≤ 0.25. A noticeable damping the intensities of BeSe-type modes with increasing fraction of Mg and Mn dopant is observed in comparison to the strengths of BeSe-type modes in Zn 1-x Be x Se crystals.