Anomalous behaviour of optical phonon modes in ZnSe epitaxial layers
✍ Scribed by O. Pagès; M. A. Renucci; O. Briot; R. L. Aulombard
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 263 KB
- Volume
- 28
- Category
- Article
- ISSN
- 0377-0486
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✦ Synopsis
Raman measurements on ZnSe/GaAs heterostructures show unusual behaviour of the optical phonon modes from ZnSe. High epitaxy rates are responsible for both poor structural quality at the interface and Fermi level pinning by carrier traps. The Ðrst e †ect gives rise, beyond a critical thickness, to polycrystalline growth associated with the activation of a theoretically forbidden TO-ZnSe mode. The second e †ect induces a spectacular enhancement of the interfacial LO-ZnSe mode strength. The competition between the latter local electric Ðeld e †ect and absorption in the upper disoriented part of the layer may result in the quasi-total extinction of the LO-ZnSe mode. 1997