Raman scattering of cadmium oxide epilayers grown by metal-organic vapor phase epitaxy

Abstract

We present a lattice-dynamics study of rocksalt cadmium oxide (CdO). We use Raman scattering to investigate a series of high-quality CdO epilayers grown on sapphire substrates by means of metal-organic vapor phase epitaxy. Two main features are found to dominate the Raman spectra of CdO: a sharp peak at ∼265 cm−1 and a broad feature at ∼390 cm−1. To assign these and other weaker second-order features that appear in the Raman spectra, we have carried out an ab initio calculation of the phonon dispersion in CdO. From the calculated two-phonon density of states (PDOS) we tentatively assign the peak at 265 cm−1 to a 2TA(L) mode. The broadband centered at ∼390 cm−1 seems to reflect the high two-PDOS in the 300–450 cm−1 spectral region.

High-pressure Raman scattering of CdO thin films grown by metal-organic vapor phase epitaxy

“…7 This band can be decomposed in 4 contributions, which in Fig. 3 are labeled as B 1 , C 1 , D, and E. The pressure behavior of the features is plotted in Fig.…”

“…On the other hand, the temperature behavior of this band indicates that it arises from a phonondifference second-order mode. 7 Thus, this band can be assigned to a LA-TA(L) mode.…”

“…6 Recently, we have reported Raman scattering studies on CdO epilayers exhibiting strong second-order modes that were assigned on the basis of ab initio calculations of the phonon dispersion curves. 7 Pressure-induced frequency shifts of the Raman bands strongly depend on the nature (optical or acoustic) and number of phonons involved in the Raman-scattering processes. Thus, the application of high hydrostatic pressures to study the vibrational properties of CdO may provide further information about the assignments of the second-order Raman bands.…”

Morphology-dependent space charge polarization and dielectric relaxation of CdO nanomorphotypes

“…6,7 Recently many researchers have shown interest on synthesis of CdO nanomaterials especially in diverse morphotypes, because of its potential applications in electronic storage devices, optoelectronics, gas sensing, solar cells and flat panel displays. [8][9][10][11] However, no report is observed on the study of dielectric properties of nanostructures as a function of different morphologies.…”

Optical and structural studies of phase transformations and composition fluctuations at annealing of Zn1-xCdxO films grown by dc magnetron sputtering

“…Іn principle, only the second-order Raman scattering is allowed in rocksalt CdO. Taking into account the results presented in [25], in the Raman spectra of annealed O Cd Zn…”