Raman scattering by the E{sub 2h} and A{sub 1}(LO) phonons of In{sub x}Ga{sub 1-x}N epilayers (0.25 < x < 0.75) grown by molecular beam epitaxy

Journal Article · Thu Mar 15 00:00:00 EDT 2012 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3693579· OSTI ID:22036829

Oliva, R; Ibanez, J; Cusco, R; Artus, L ^[1]; Kudrawiec, R ^[2]; Serafinczuk, J ^[3]; Martinez, O; Jimenez, J ^[4]; Henini, M ^[5]; Boney, C; Bensaoula, A ^[6]

---

1. Institut Jaume Almera, Consell Superior d'Investigacions Cientifiques (CSIC), Lluis Sole i Sabaris s.n, 08028 Barcelona, Catalonia (Spain)
2. Institute of Physics, Wroclaw University of Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland)
3. Faculty of Microsystem Electronics and Photonics, Wroclaw University of Technology, Janiszewskiego 11/17, 50-372 Wroclaw (Poland)
4. Departamento de Fisica de la Materia Condensada, Cristalografia, y Mineralogia, Universidad de Valladolid, 47011 Valladolid (Spain)
5. Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, Nottingham NG7 2RD (United Kingdom)
6. Department of Physics, University of Houston, 4800 Calhoun, Houston, Texas 77004 (United States)

We use Raman scattering to investigate the composition behavior of the E{sub 2h} and A{sub 1}(LO) phonons of In{sub x}Ga{sub 1-x}N and to evaluate the role of lateral compositional fluctuations and in-depth strain/composition gradients on the frequency of the A{sub 1}(LO) bands. For this purpose, we have performed visible and ultraviolet Raman measurements on a set of high-quality epilayers grown by molecular beam epitaxy with In contents over a wide composition range (0.25 < x < 0.75). While the as-measured A{sub 1}(LO) frequency values strongly deviate from the linear dispersion predicted by the modified random-element isodisplacement (MREI) model, we show that the strain-corrected A{sub 1}(LO) frequencies are qualitatively in good agreement with the expected linear dependence. In contrast, we find that the strain-corrected E{sub 2h} frequencies exhibit a bowing in relation to the linear behavior predicted by the MREI model. Such bowing should be taken into account to evaluate the composition or the strain state of InGaN material from the E{sub 2h} peak frequencies. We show that in-depth strain/composition gradients and selective resonance excitation effects have a strong impact on the frequency of the A{sub 1}(LO) mode, making very difficult the use of this mode to evaluate the strain state or the composition of InGaN material.

• OSTI ID: 22036829
• Journal Information: Journal of Applied Physics, Vol. 111, Issue 6; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
36 MATERIALS SCIENCE
CONCENTRATION RATIO
CRYSTAL GROWTH
EXCITATION
FLUCTUATIONS
GALLIUM NITRIDES
INDIUM NITRIDES
LAYERS
MOLECULAR BEAM EPITAXY
PHONONS
RAMAN SPECTRA
RANDOMNESS
RESONANCE
SEMICONDUCTOR MATERIALS
STRAINS
ULTRAVIOLET SPECTRA