Оптические свойства легированных нанопроволок во внешних электрическом и магнитном поляx

The impurity absorption of light in quantum wires in the presence of external electric and magnetic fields directed parallel to each other and perpendicular to the axis of the nanowire is studied theoretically. Impurities doped in a quantum wire are modeled by a zero-range potential. Expressions are obtained for the light absorption coefficient and the features of impurity absorption of light are studied for all possible directions of polarization of the light wave. In particular, in the presence of external fields, some optical transitions, which are forbidden in the absence of fields, become allowed. The frequency dependences of the light absorption coefficient and the influence of electric and magnetic fields on the value of the impurity light absorption coefficient are investigated. The possibility of controlling the optical characteristics of nanowires using an electric field is shown.

Локализованные экситоны в спектре оптического поглощения оксида цинка, легированного марганцем

The results of the study of optical absorption and EPR signals of single crystals of zinc oxide doped with manganese are presented. A broad impurity absorption band with the threshold energy about 2.1 eV, which was treated as a result of charge transfer transitions, has been observed for a long time in ZnO : Mn absorption spectra. In absorption spectra of a polarized light at 4.2 and 77.3 K, we first detected several lines of different intensity in a 1.877–1.936 eV range of energies of the light quanta. The observed lines are attributed to a donor exciton [( d ^5 + h ) e ] that emerges as a result of the Coulomb binding a free s electron and a hole, which is localized on p – d hybridized states. The EPR spectra of Mn^2+ ion signals, when corresponding to the impurity absorption band exposed to light, are found to be not photosensitive. The obtained results indicate that the ZnO : Mn impurity absorption is due to transitions from antibonding p – d hybridized DBH states to the conduction band.

The Effects of Deoxidants on Ge-Se-Te Chalcogenide Glasses

In order to decrease the impurity absorption bands of Ge-Se-Te chalcogenide glasses in IR region. Three different kinds of deoxidants including Mg(magnesium), Al(aluminium) and Ca(calcium) were chosen. Properties measurements including density, Vis-NIR and infrared (IR) transmission spectra were adopted to analyze the relationship between impurity absorption bands and deoxidants. The concentrations of impurities in glass samples with different content of Mg were calculated by method of optic spectra. The results show that Mg is a better choice as deoxidant for chalcogenide glasses compared to Al and Ca. The values of main impurity concentration decrease from 4417.833 to 0 ppmw for Ge-O and from 55.236 to 0 ppmw for Si-O with increasing content of Mg, respectively. At least 200ppm Mg is needed to minimize the main absorption bands in IR region and G5 glass incorporated with 400ppm Mg has minimum concentration of impurities which means that it possesses the optimal transmission properties.