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摘要
The properties of polycrystalline wurtzite Zn1-xMgx (0 <= x <= 0.15) have been studied by powder X-ray diffraction (XRD), including an analysis of the X-ray line-broadening and by luminescence, absorption, and Raman spectroscopies. We have previously established from synchrotron X-ray diffraction that with increasing Mg-concentration, the c-axis compresses, and the of center cation displacement within each tetrahedral (Zn,Mg)O4 unit decreases. Here we perform a sizes-train line-broadening analysis of the XRD peaks, which reveals that Mg-substitution reduces the coherent crystallite size and also develops the lattice microstrain. Optical properties of the samples have been characterized by diffuse-reflectance absorption spectroscopy and luminescence spectroscopy. Both the optical band gap and the band-edge emission energies gradually increase with the Mg-concentration in Zn1-xMgxO. The Mg-substituted samples show broader band tails near the absorption edge, due to an increase in crystal imperfections. The peak broadening of the E-2(high) Raman mode upon Mg-substitution is also ascribed to the phonon shortening lifetime mechanism via crystal defects.
- 出版日期2008-11
