Optical properties and structural characteristics of ZnMgO grown by plasma assisted molecular beam epitaxy
- Walter Schottky Institut, Technische Universitaet Muenchen, Am Coulombwall 3, 85748 Garching (Germany)
- I. Physikalisches Institut, Justus-Liebig-Universitaet, 35392 Giessen (Germany)
Wurtzite Zn{sub 1-x}Mg{sub x}O thin films with Mg contents between x=0 and x=0.37 were grown on c-plane sapphire substrates by plasma assisted molecular beam epitaxy using a MgO/ZnMgO buffer layer. The a-lattice parameter is independent from the Mg concentration, whereas the c-lattice parameter decreases from 5.20 A for x=0 to 5.17 A for x=0.37, indicating pseudomorphic growth. The near band edge photoluminescence shows a blueshift with increasing Mg concentration to an emission energy of 4.11 eV for x=0.37. Simultaneously, the energetic position of the deep defect luminescence shows a linear shift from 2.2 to 2.8 eV. Low temperature transmission measurements reveal strong excitonic features for the investigated composition range and alloy broadening effects for higher Mg contents. The Stokes shift as well as the Urbach energy is increased to values of up to 125 and 54 meV for x=0.37, respectively, indicating exciton localization due to alloy fluctuations.
- OSTI ID:
- 21185981
- Journal Information:
- Journal of Applied Physics, Vol. 105, Issue 2; Other Information: DOI: 10.1063/1.3065535; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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