Structural and magnetic properties in Mn-doped GaN grown by metal organic chemical vapor deposition Appl. Phys. Lett. 92, 152116 (2008); 10.1063/1.2909545 Anomalous magnetic properties of the ferrimagnetic semiconductor on Ga-doped sulphur spinel
Raman spectra of Ga1−xMnxN crystals grown by the resublimation method have been investigated. New bands around 300 and 667 cm−1, as well as a broad structure near 600 cm−1, not observed in undoped GaN have been found. The temperature dependence of major Raman bands has been measured. The simple model of GaN lattice dynamics has been presented, and the observed bands have been assigned to disorder-activated phonon modes, in good agreement with the calculated phonon density of states.
Preliminary results of Raman scattering measurements of multiwall carbon nanotubes (MWCNT) are presented. The nanotubes have been carefully dissolved, separated and then characterized by AFM. The micro-Raman spectra are taken with 514,5nm wavelength excitations in the range 4K - 400K. Basically the spectra are quite similar to the well known single wall carbon nanotube spectra, but the low frequency band is absent. The major Raman bands, observed in single wall nanotubes are found in the spectra. In particular the disorder effects are visible due to the pronounced D band at ~1350 cm-1. Metallic and semiconducting type of conductivity is distinguished through analysis of the G (LO) mode at ~1600 cm-1. A new feature in these spectra exists at ~843 cm-1. Low energy radial breathing mode absence has been explained.
Raman spectra of CulnSwSe(l-,, mixed crystals are reponed. The dependence of the mode frequencies on lhe composition is studied. Two-mode behaviour is observed for the higherfrequency phonons. One-mode behaviour is found for the low-frequency modes corresponding to the zone-edge acoustic phonons of zincblende.Solid solutions of CuInSbSez(l-z) type are considered as an alternative for CuInSe;? as an absorber in thin-film solar cells [l]. They crystallize in the chalcopyrite structure over the whole composition range. The band gap varies from 1.04 eV for CuInSe;? to 1.53 eV for CuInSz. To our knowledge no data on the lattice dynamics of this system have been
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