分子線エピタキシー法によりKBr基板上作製されたバナジルフタロシアニン薄膜

Abstract

Nonlinear optical materials are important in developing optical devices such as optical switch, modulation and memory. Therefore, they have recently attracted much attention. Vanadyl-Phthalocyanine (VOPc) is one of them. In this paper, we investigated not only the morphologies of VOPc thin film prepared on KBr substrate by molecular beam epitaxy (MBE) but also the conditions to prepared large single crystals, A 15nm-thick VOPc thin film prepared on a KBr substrate with a substrate temperature (TS : 80℃), evaporating temperature (Te : 300℃) and depositing time (t : 10 min.) has a uniform surface image of scanning electron microscopy (SEM), The film has an optical absorption peak at 810nm in the visible and infrared region, It was epitaxially grown. A VOPc thin film prepared on a KBr with another condition of Ts : 200℃ and Te : 300℃ and t : 60 min. has discrete single crystals. Their average size are about 1x0.5x0, 1 μm, The single crystal is 3x3R45°type and It was epitaxially grown judging from the images of SEM, atomic force microscoy (AFM), reflection high energy electron diffraction (RHEED) and the spectra measured with a UV/VIS spectroscopy. A VOPc thin film prepared on a KBr substrate with Ts : 250℃ and Te : 300℃ shows the absorption peak around 830nm, Therefore, the shift of the optical absorption peak for the single crystal to a longer wavelength may be related to disorder in a film epitaxially grown and/or may be due to a phase transition under a high substrate temperature.