Optical properties of MgZnO alloys: Excitons and exciton-phonon complexes

Journal Article · Fri Jul 01 00:00:00 EDT 2011 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.3606414· OSTI ID:22036652

Neumann, M D; Cobet, C; Esser, N ^[1]; Laumer, B ^[2]; Wassner, T A ^[3]; Eickhoff, M ^[2]; Feneberg, M; Goldhahn, R ^[4]

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1. Leibniz-Institut fuer Analytische Wissenschaften - ISAS - e.V., Albert-Einstein-Str. 9, 12489 Berlin (Germany)
2. I. Physikalisches Institut, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 16, 35392 Giessen (Germany)
3. Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, 85748 Garching (Germany)
4. Institut fuer Experimentelle Physik, Otto-von-Guericke-Universitaet Magdeburg, 39106 Magdeburg (Germany)

The characteristics of the excitonic absorption and emission around the fundamental bandgap of wurtzite Mg{sub x}Zn{sub 1-x}O grown on c-plane sapphire substrates by plasma assisted molecular beam epitaxy with Mg contents between x = 0 and x = 0.23 are studied using spectroscopic ellipsometry and photoluminescence (PL) measurements. The ellipsometric data were analyzed using a multilayer model yielding the dielectric function (DF). The imaginary part of the DF for the alloys exhibits a pronounced feature which is attributed to exciton-phonon coupling (EPC) similar to the previously reported results for ZnO. Thus, in order to determine reliable transition energies, the spectral dependence is analyzed by a model which includes free excitonic lines, the exciton continuum, and the enhanced absorption due to EPC. A line shape analysis of the temperature-dependent PL spectra yielded in particular the emission-related free excitonic transition energies, which are compared to the results from the DF line-shape analysis. The PL linewidth is discussed within the framework of an alloy disorder model.

• OSTI ID: 22036652
• Journal Information: Journal of Applied Physics, Vol. 110, Issue 1; Other Information: (c) 2011 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
COUPLING
CUBIC LATTICES
DIELECTRIC MATERIALS
ELLIPSOMETRY
ENERGY GAP
EXCITONS
LAYERS
MAGNESIUM COMPOUNDS
MOLECULAR BEAM EPITAXY
OPTICAL PROPERTIES
PERMITTIVITY
PHONONS
PHOTOLUMINESCENCE
PLASMA
SEMICONDUCTOR MATERIALS
SUBSTRATES
TEMPERATURE DEPENDENCE
ZINC OXIDES