Local vibrational modes of hydrogen in GaN: Observation and theory

• Published in: Physica. B, Condensed matter Vol. 376; pp. 464 - 467
• Main Authors: Pereira, R.N., Bech Nielsen, B., Stavola, M., Sanati, M., Estreicher, S.K., Mizuta, M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2006
• Subjects: GaN; Hydrogen; Implantation; Local vibrational mode; 78.55.Ap; 82.30.Rs; Local vibrational mode; GaN; Hydrogen; Implantation; 61.72.Ss; 61.72.Tt
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2005.12.119

Gallium nitride (GaN) single crystals were implanted with protons (deuterons) at temperatures below 20 K and studied by infrared absorption spectroscopy at 8 K without any intermediate heating of the samples. A strong absorption line was observed at 1456 cm - 1 after proton implantation. The annealing of the 1456 - cm - 1 line at about 225 K is correlated with the appearance of two absorption lines at 3027 and 3139 cm - 1 , which were shown previously to represent N–H stretch modes of V Ga -H defects in GaN. The observation of the 1456 - cm - 1 line after low-temperature implantation, together with the observation of a correlated annealing for the 1456 - cm - 1 line and V Ga -H centers, suggests that the line originates from isolated H in GaN. First-principles local-density-functional theory was used to calculate the H-related local mode frequencies of different structures and charge states of isolated H in GaN. The likely candidates for the assignment of the 1456 - cm - 1 line are discussed on basis of mode frequencies predicted for different structures.