期刊
JOURNAL OF APPLIED PHYSICS
卷 105, 期 2, 页码 -出版社
AMER INST PHYSICS
DOI: 10.1063/1.3065535
关键词
buffer layers; deep levels; defect states; excitons; II-VI semiconductors; lattice constants; molecular beam epitaxial growth; photoluminescence; plasma materials processing; semiconductor growth; semiconductor thin films; spectral line shift; wide band gap semiconductors; zinc compounds
资金
- Deutsche Forschungsgemeinschaft [(EI 518/2-1)]
- German Excellence Initiative via the Nanosystems Initiative Munich (NIM)
Wurtzite Zn(1-x)Mg(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.
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