Effects of alloying and localized electronic states on the resonant Raman spectra of Zn1−xMgxO nanocrystals

Abstract

Using resonant Raman spectroscopy, the authors report on the alloying effect and localization of electronic states in Zn1−xMgxO (x<0.15) nanostructures with average sizes in the range of 20–150nm. Anomalous intensity enhancement of the second-order longitudinal optical phonon has been observed, which is due to Fröhlich interaction via the localized exciton as the resonant intermediate electronic states. The alloying-induced disorder due to Mg incorporation led to the enhancement of exciton localization as well as the asymmetric broadening of longitudinal optical phonon line shape. The composition in ZnMgO could be determined by the first-order longitudinal optical phonon frequency via a bowinglike quadratic fit. This simple relationship is in perfect match to the modified random-element-isodisplacement model and provides a nondestructive approach to probe the quantitative composition distributions in wurtzite ZnMgO alloy system.

Interfacial and bulk polaron masses in Zn1−xMgxO/ZnO heterostructures examined by terahertz time-domain cyclotron spectroscopy

“…1(b). This phonon blueshifts with increasing x, in agreement with previous studies, 14,15 Terahertz time-domain spectroscopy 17,18 was utilized to determine the complex magnetoconductivity in the frequency range 100 GHz < ω/2π <2 THz. Samples were placed in the variable-temperature insert of a split-coil superconducting magnet, which applied a magnetic field B along the c-axis.…”

Resonant Raman scattering based approaches for the quantitative assessment of nanometric ZnMgO layers in high efficiency chalcogenide solar cells

“…The figure includes also data previously reported in the literature 28, 30 , together with those derived from the analysis of the spectra shown in Fig. 3.…”

“…Starts: experimental data from layers series (i). Circles: data reported from references 28, 30 . Full line shows the fitting of the data according to Equation 1. …”

Comparative study of group-II alloying effects on physical property of ZnGaO transparent conductive films prepared by RF magnetron sputtering

“…It is, while, noticeable that these phonon peaks are at higher frequencies than those in the un-doped ZnO as well as weak and broad. These features are often observed in polar alloy semiconductors and have been generally believed to be due to the reduced mass change of oscillating pairs [29]. The ZnO non-polar E 2 modes are mainly excited by the vibration of oxygen atoms (E 2 -high) and Zn atoms (E 2 -low) and in general, as the crystal is alloyed, the phonons can be confined in space, owing to the potential fluctuation by the alloy disorder, which result in the relaxation of the selection rule in Raman scattering [30].…”