Structural properties of copper phthalocyanine (CuPc) powder and its thin films coated on glass plate are investigated using X-ray diffraction, Raman scattering and optical absorption techniques. These experiments are carried out at room temperature on CuPc powder and as-coated, 320 C and 520 C annealed, CuPc thin films. From the X-ray diffraction (XRD), we find that the CuPc powder exists in monoclinic phase, as-coated film is in orthorhombic a-phase and the film annealed at 320 C exists in monoclinic b-phase with different lattice parameters as compared to those of the powder phase. The XRD peaks in 520 C annealed film do not show the presence of CuPc but indicate the presence of copper oxide (CuO) nanoclusters of approximately 15 nm size. The optical Raman phonon frequencies of CuPc powder, as-coated and 320 C annealed CuPc films show a slight shift in the intramolecular high frequency modes. Whereas, their low frequency Raman spectra from intermolecular modes are characteristically different indicating different phases. The different characteristic behavior of the optical absorption spectra of the as-coated and 320 C annealed CuPc films corroborate the structural changes in the annealed film.

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Raman scattering and photoluminescence (PL) measurements on (100) oriented n-type crystalline silicon (c-Si) and porous silicon (PS) samples were carried out. PS samples were prepared by anodic etching of c-Si under the illumination of light for different etching times of 30, 60 and 90 min. Raman scattering from the optical phonon in PS showed the redshift of the phonon frequency, broadening and increased asymmetry of the Raman mode on increasing the etching time. Using the phonon confinement model, the average diameter of Si nanocrystallites has been estimated as 2⋅ ⋅9, 2⋅ ⋅6 and 2⋅ ⋅3 nm for 30, 60 and 90 min samples, respectively. Similar size of Si crystallites has been confirmed from the high resolution transmission electron microscopy (HRTEM). Using 2TO phonon mode intensity, we conjectured that the disordered Si region around the pores present in 30 min PS dissolved on etching for 90 min. The photoluminescence (PL) from PS increased in intensity and blue shifted with etching time from 2⋅ ⋅1-2⋅ ⋅3 eV. Blue shifting of PL is consistent with quantum confinement of electron in Si nanocrystallites and their sizes are estimated as 2⋅ ⋅4, 2⋅ ⋅3 and 2⋅ ⋅1 nm for 30, 60 and 90 min PS, respectively which are smaller than the Raman estimated sizes due to temperature effect. Unambiguous dominance of quantum confinement effect is reported in these PS samples.

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