Mykhaylo M. Dvoynenko

An exact solution of the Lippmann–Schwinger equation in one dimension

We consider a one-dimensional scattering problem and establish a system of two integral equations for the local (self-consistent) electric field. The equations are derived using the standard Green’s function method. Their solution yields the local fields at any point of the system. To illustrate the efficacy of this approach, we apply it to a film and obtain analytical solutions that are identical to the Fabry–Perot solution. Some potential applications of the approach are also discussed.

Far-IR investigation of thin InGaN layers

AbstractWehavemeasuredthereflectionspectraofultra-thinIn x Ga 1 x N/GaNlayersonsapphiresubstrateswiththickGaNbufferlayerattemperaturesof300,200and90K.Wecouldnotobserveanysignalassociatedwiththeselayers.Comparingthemeasuredspectrawiththecalculatedonesforwell-mixedIn x Ga 1 x Nlayers,weconcludedthatoursampleshadnomixedstate.WealsoconcludedthattheseparatedInandNatomsdidnotformInNlayers.ThereasonforthefactthatwedidnotobservearesponsefromtheselayersistheinhomogeneousbroadeningoftheIn x Ga 1 x Nreflectionline.Wehavecalculatedtheabsorptionspectraofsmallparallelepiped-likeInNparticlesintheGaNmatrix.Ithasshownthattheabsorptionlinewidthforsuchsmallparallelepiped-likeparticlesisbiggerthanthatforthebulkInNmaterial.WeconcludedthatoursamplescontainedseparatedInanddemonstratedformationofInNclusters.r 2002ElsevierScienceB.V.Allrightsreserved. PACS: 78.30.Fs;78.66.Fd;78.67.Bf;42.25.BsKeywords: IRspectroscopy;InGaN;Mixedcrystals;Absorptionofnanoparticles 1. IntroductionAt present the wide-gap GaN-based nitridesemiconductorsattractagreatdealofattentionin research and development, because of theirusefultechnologicalapplicationsinlight-emittingdiodesinthenear-UV-blue-greenspectralregion[1],andtheirpotentialitiesforuseinthehigh-temperatureelectronics[2].In

Optical phonon localization in self-assembled Ge islands

Abstract We present a Raman scattering study for self-organized Ge islands on Si substrate carried out at 10 K . By means of difference Raman spectroscopy technique, we have separated the Raman signals from the Ge islands and Si substrate. The wetting layer thickness and strain were estimated from the line width and frequency peak. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. The strain is decreased with an increase of the thickness.

The photoluminescence investigation of ZnxMn1−xTe films

Abstract We have measured photoluminescence spectra of Zn1−xMnxTe films grown on a GaAs substrate with ZnSe buffer layer at the low temperature (10 K ) . These spectra were taken with the use of an Ar ion laser excitation (=488.8 nm ) . The value x equals 0, 0.045, 0.117, 0.152, 0.1811 and 0.268. For the pure ZnTe, we observed the well-resolved five exciton lines that can be attributed to free and bound excitons. The integral (total) intensity of photoluminescence lines from the sample with x=0.045 is approximately in five times higher than from the sample ZnTe. The photoluminescence from the samples is associated with excitons bounded on Mn. With the increasing of the Mn, the line width of the main peak increases essentially. The FWHL for the ZnTe film is about 3 meV and for the Zn0.74Mn0.26Te film is 35 meV . The essential increase of the line width indicates an increase of an inhomogeneous structure.

Phonon modes of short-period (GaAs)n/(AlAs)n superlattices

In the work finding optical phonon energies from photoluminescence spectra and interpretation of their dependence on quantum well width are carried out. Remarkable decreasing both GaAs and AlAs phonon energies has been observed. It is shown that this dependence differs noticeably from that obtained from Raman spectra. The possible origin of this phenomenon is considered.

Raman scattering study for self-organized Ge quantum dots formed on Si substrate

A Raman scattering study for self-organized Ge dots on Si substrate is presented. Raman signals from the Ge islands and Si substrate have been separated, by means of difference Raman spectroscopy technique. The wetting layer thickness and strain were estimated from the line width and the position of the peak. The estimated wetting layer thickness values are comparative with the Ge dot height obtained from microscopy measurements. As explained, the strain is observed to decrease with an increase of the Ge island height and the wetting layer thickness.