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Raman Scattering in Resonance with Acceptor‐Bound Excitons in GaN
Author(s) -
Kaschner A.,
Hoffmann A.,
Thomsen C.
Publication year - 2001
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/1521-3951(200102)223:3<r11::aid-pssb999911>3.0.co;2-7
Subject(s) - physics , resonance (particle physics) , humanities , engineering physics , philosophy , atomic physics
Resonance effects in light scattering from solids occur in the range of frequencies of the electronic absorption bands. Resonant Raman scattering, i.e., a strong enhancement of the Raman scattering cross section, can be observed if the energy of the incoming or scattered photons matches real electronic states in the material. This results from the denominator in the Raman scattering cross section tending to zero. One refers to incoming and outgoing resonance, respectively (see, e.g., (1)). In GaN resonant Raman scattering was reported under excitation slightly above the band gap (2, 3). The appearance of multiple LO phonons due to Fröhlich interaction indicated the strong polar character of the Ga-N bond. Furthermore, this technique was applied to study compositional non-uniformity in the ternary alloy InGaN (4, 5). However, resonance Raman scattering at bound excitons as reported for CdS is not known for GaN (6, 7). To the best of our knowledge we report Raman scattering in resonance with acceptor-bound excitons in GaN for the first time. Experimental Details The sample under study was a not intentionally doped 220 µm thick GaN film grown by hydride vapor phase epitaxy. Sapphire (0001) with a sputtered ZnO buffer layer was used as substrate (8). Raman spectra were taken in backscattering geometry z(..)z under excitation with the 363.8 nm Ar + line. The measurements were carried out with a Dilor UV spectrometer having a resolution of 3 cm -1 . In order to study the temperature dependence of the excitonic recombination cathodoluminescence (CL) experiments were performed.