Temperature dependence of Raman scattering in Co-doped AlN whiskers |
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| Authors: | L B Jiang H Li S B Zuo H Q Bao W J Wang X L Chen |
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| Institution: | 1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, P.O. Box 603, Beijing, 100190, China
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| Abstract: | Raman studies are reported for the A
1 (TO), E
2 (high) and E
1 (LO) phonons of Co-doped AlN whiskers from 78 K to 778 K. The temperature dependence of the Raman shifts and line widths
of these phonons can be well described by an empirical model which takes into account the contribution of the thermal expansion
of the lattice and the symmetric decay of phonons into two and three identical phonons with lower energy. Our results show
that the three-phonon process is the dominant decay channel in A
1 (TO), E
2 (high) and E
1 (LO). The symmetric decay of A
1 (TO) may be attributed to the production of two LA phonons near the M symmetry point of the Brillouin zone. For E
2 (high), the symmetric decay may be near the M and L symmetry points. The E
1 (LO) phonon, whose decay behavior has not been identified in AlN, may decay near the H and K symmetry points of the Brillouin zone. Compared with undoped AlN, the stronger temperature dependence of the A
1 (TO) and E
2 (high) phonons in Co-doped AlN whiskers was observed, which is probably due to the distortion of the lattice and the much
larger tensile stress after doping Co into AlN. |
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| Keywords: | |
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