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This study reports the use of surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS), both independent and in combination, to investigate Raman enhancement of films under different confinement geometries. The experiments are performed on ultrathin cobalt phthalocyanine (CoPc) films deposited on specially designed SERS structures. The SERS structures are fabricated by electron-beam lithography and contain nanostructured gold films and gold dimer arrays with controlled size and internanocluster distance. Such structures allow investigation of the effects of nanocluster size and internanocluster distance, excitation wavelength, and polarization of light upon the electromagnetic SERS enhancement. Significant enhancement of the Raman scattering by CoPc is observed under 632.8 nm excitation because of the double resonance originating from the energy match between the laser excitation and the localized surface plasmon and electronic transitions in CoPc. The SERS signal of CoPc is further enhanced by decreasing the internanocluster distance. Maximum SERS enhancement occurs when the polarization of the incident light is perpendicular to the dimer axis. Under 514.5 nm excitation, nanostructured gold films give greater enhancement than any of the nanocluster arrays, with the highest enhancement realized using the so-called “gap-mode TERS” wherein the SERS structures are probed in the TERS condition. The TERS experiment is performed using a customized TERS setup and all-metal atomic force microscopy tips custom fabricated. In terms of obtaining the ultimate sensitivity in Raman spectroscopy, further enhancement is achieved by confining the electromagnetic field in a gap between two metallic nanostructures either by using SERS or by combining SERS and TERS.

CdZnS quantum dots (QDs) with systematically varied Zn content (from 0 to 100%) are formed in an organic matrix using the Langmuir–Blodgett technique. Annealing of the QD structures leads to a removal of the organic matrix and an increase in the Zn content for free-standing CdZnS QDs. After annealing, the size of QDs as determined from UV–vis absorption experiments is in good agreement with electron microscopy measurements. Analysis of UV–vis absorption and Raman scattering data demonstrates strong changes in the content of the CdZnS QDs upon annealing. A model of the process of QD formation is developed using the precipitation model and is found to adequately describe the experimental results.

Phonon spectra of CdS, ZnS, PbS, CuS, Ag2S, and ZnO quantum dots formed by using the Langmuir–Blodgett technology are investigated by Raman and infrared spectroscopies. The Raman spectra of structures show peaks corresponding to the scattering by longitudinal and transverse optical (LO and TO) phonons localized in quantum dots that confirm the formation of nanocrystals. In addition to TO and LO phonon modes, the modes observed in the IR spectra between the frequency positions of LO and TO phonons are attributed to the surface optical phonons in quantum dots.

We present the results of an infrared (IR) spectroscopic investigation of interfaces between two hydrophilic Si wafers bonded at low temperature. Multiple internal transmission IR spectra were recorded of the bonds, with different chemical pretreatments of Si surfaces employed before bonding. The analysis of IR spectra shows that the number of O–H and H–Si–Ox species at the interface depends strongly on the chemical pretreatment type, which determines the bonding energy. The annealing procedure used in the bonding process leads to dissociation of water molecules, oxidation of silicon at the interfaces, and diffusion of hydrogen into silicon oxide layer formed at the interface. The difference in bonding processes is discussed.

Multiple internal reflection and transmission IR spectra of hydrophobic and hydrophilic Si wafers, Si wafers with thermally grown SiO2 layers, and Si wafers bonded at high and room temperature were investigated. It was found that the surface of the as-prepared hydrophobic wafer is terminated by hydrogen and water molecules, while the IR spectra of hydrophilic wafer demonstrate only the presence of water molecules at the surface. IR spectra of Si wafers covered by a thermally grown SiO2 layer exhibit a number of the strong absorption bands assigned to combinational phonon bands in SiO2. The wafer bonding leads to the appearance of siloxane and hydroxyl groups at the buried interface whose absorption bands were observed in IR spectra. A rearrangement of atoms at the buried interface takes place after annealing of Si bonded wafers. IR spectra of room temperature bonds show a large number of water molecules and presence of the hydrogen in the oxide layer at the interface.

The optical phonon modes in short-period GaAs/AlAs superlattices were investigated by means of Raman spectroscopy and far-infrared reflection spectroscopy using a grating coupler technique. Grating couplers provide a wave vector transfer parallel to the layers, enabling study of in-plane dispersion of the phonon modes in the superlattice structure. The mixing of confined and interface optical modes was observed as the in-plane phonon wave vector was varied. The experimental frequencies of the superlattice optical modes obtained from infrared and Raman spectra are in good agreement with calculations performed using a dielectric continuum model.