Infrared spectroscopy of pentacene thin film on SiO2 surface

Characterization of molecular organization in pentacene thin films on SiO2 surface using infrared spectroscopy, spectroscopic ellipsometry, and atomic force microscopy

“…The first one is anisotropic with uniaxially distributed molecules on Si/SiO 2 surface (vide infra) whereas the other is composed of randomly oriented microcrystals. Our findings of vibrations in deposited film using GATR measurements agree with other experimental works for crystalline pentacene samples and thin films as well as with the computations with the B3LYP DFT level of calculations [13,14,16,34,35]. The positions of the most intense IR peaks with defined vibrational modes are marked in Fig.…”

“…Previous experimental verification of computed vibrational modes was based only on the most intense peaks extracted from the spectra provided by reflection-absorption infrared (RAIRS) method [14], polarized multiple internal reflection [16,37], and transmission spectra [14,39] where the low intensity peaks were out of detection limit. In the GATR spectra most of the assignments correspond to the calculated ones [14].…”

“…Single reflection Ge-GATR with polarized irradiation is a powerful tool for investigation of a thin film on a silicon substrate [22,23]. Although thin pentacene films were studied previously by IR spectroscopy in the multiple internal reflection geometry [16] and by reflection-absorption mode on gold surface [14,24], the GATR method is a new approach for pentacene thin film investigation. To our best knowledge pentacene alignment has not been yet studied by polarized GATR infrared spectroscopy.…”

“…Thin film structures of pentacene were investigated by X-ray diffraction (XRD) [8,11], atomic force microscopy (AFM) [9,11], infrared [12][13][14][15][16] and Raman spectroscopy [11], and ellipsometry [10,[17][18][19][20] to elucidate the impact of ordering and grain morphology on OFET performance [9,21]. Thin pentacene films on common dielectric layers such as SiO 2 exhibit a coexistence of morphologically multiple phases which, after attaining the appropriate thickness, grow sequentially during deposition.…”

Growth related properties of pentacene thin film transistors with different gate dielectrics

“…The pentacene molecule belongs to the D2h group symmetry and the three corresponding molecular axis are shown in insert. According to Hosoi et al [40], bands at 907 cm À1 and 1296 cm À1 should be assigned to Z and X polarized mode respectively, whereas bands at 1443, 1499 and 1537 cm À1 are polarized along the Y-axis. Only X and Z polarized modes (1296 cm À1 and 906.6 cm À1 ) are present in the spectrum of pentacene film deposited on e-beam Ta 2 O 5 ( Fig.…”