Disorder-Activated Scattering and Two-Mode Behavior in Raman Spectra of Isotopic GaN and AlGaN
✍ Scribed by N. Wieser; O. Ambacher; H. Angerer; R. Dimitrov; M. Stutzmann; B. Stritzker; J.K.N. Lindner
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 184 KB
- Volume
- 216
- Category
- Article
- ISSN
- 0370-1972
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✦ Synopsis
Micro-Raman spectroscopy has been applied to isotopically pure Ga i N (i = 14, 15) epitaxial films in which structural disorder was introduced by ion implantation or mechanical damage. A pair of Raman peaks appearing at about 300 (300) and 667 (646) cm ± ±1 is consistent with the anion mass 14 (15) suggesting disorder activation of the silent B 1 modes, where the low-frequency mode is related to the Ga vibration (no N isotope shift) and the high-frequency mode to the N vibration (full N isotope shift). Isotopically pure Al 0.5 Ga 0.5 i N indicates respective activation of the silent B 1 modes due to alloying disorder and confirms a two-mode behavior of the E 2 mode. In agreement with recent IR measurements and theoretical predictions, we additionally provide evidence for an E 1 (TO) two-mode behavior in Raman scattering as obtained from polarisation dependent measurements on Al x Ga 1± ±x N epilayers.