We report the results of non‐resonant and resonant Raman scattering in orthorhombic nanocrystalline CuInS
2
semiconductor, supported by density functional first principle lattice dynamics ...calculations. A larger number of dominant phonon modes in comparison with standard tetragonal CuInS
2
phases is shown to be associated with peculiarities of cation sublattice ordering and is the “fingerprint” of the corresponding structural polymorph. Good overall agreement is found between theoretical and experimental phonon mode frequencies.
The properties of surface and buried interface silicon oxide layers in low- and high-temperature SiSi bonded wafers, were investigated using infrared spectroscopy, spectroscopic ellipsometry (SE) ...and high resolution transmission electron microscopy (HRTEM). Infrared transmission spectra show the absorption by SiOSi vibrations originating from surface and interface silicon oxide. To distinguish the contribution of surface and buried interfaces oxide in the spectra, the surface oxide was removed by chemical etching. The interface oxide thickness was calculated from curve fitting of infrared transmission spectra of the etched bonds. An excellent agreement of values of the interface oxide thicknesses determined using this method with those obtained from HRTEM measurements was found. The behaviour of longitudinal and transversal optical (LO and TO) phonons in surface silicon oxide was analysed. The frequency position of TO and LO modes shifts towards higher energy and the LO-TO splitting decreases upon annealing. This behaviour can be explained in terms of a thermal relaxation model.
Optical spectroscopies: Raman, infrared (IR) and photoluminescence (PL) were used to investigate the influence of the substrate temperature on the film formation of the organic molecule ...3,4,9,10-perylenetetracarboxyl dianhydride (PTCDA) on hydrogen-passivated silicon(100) substrates. Raman spectra exhibit four phonon bands below 125cm−1, indicating the crystalline nature of the films. The spectral changes of both Raman- and infrared-active modes reflect that the size of the individual crystals increases with the substrate temperature during growth. Moreover, they support an increase in the content of the α-phase at the expense of the β-phase. The rising background in the high frequency range of the Raman spectra is related to an enhancement of the PL efficiency connected to a reduced number of non-radiative centres of recombination. Time-resolved PL measurements reveal that the PL decay time increases with the substrate temperature, approaching the value characteristic for a PTCDA single crystal.
In this paper our recent research on Ge and PbS nanoparticles embedded in ZrO 2 will be reviewed. Ge nanoparticles have been deposited by rf-cosputtering of ZrGe 2 O 2.9 /ZrO 2 superlattices and ...subsequent annealing. ZrO 2 and the phase separated Ge crystallizes at 650°C into nanocrystalline layers. These layers show a luminescence signal at 2.5 eV, which is contributed to defect luminescence. PbS nanoparticles have been fabricated using wet chemical methods and embedded in the ZrO 2 matrix by sol-gel deposition. In this case a luminescence signal at 1.3 μm has been detected after annealing at 100°C.
Thin heterostructures and mixed layers of tris(8–hydroxyquinoline)-aluminum(III) (Alq
3) and N,N′-Di-(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine (
α-NPD) were deposited on large-area ...silicon substrates by means of the recently developed organic vapor phase deposition (OVPD) method. Variable angle spectroscopic ellipsometry (VASE) was employed as a non-destructive technique to measure the thickness and optical constants of the single layers deposited by OVPD. Using the determined optical constants it is demonstrated that spectroscopic ellipsometry is capable of determining the thicknesses of individual layers in Alq
3/
α-NPD heterostructures. Furthermore, the percentage of mixing in uniformly mixed Alq
3−
α–NPD layers can be determined from the analysis of the ellipsometric data. A simulation of ellipsometric parameters
Ψ
and
Δ demonstrates that ellipsometry is a very suitable tool for in situ real-time thickness monitoring during the OVPD deposition process.
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