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Semiconductor Physics, Quantum Electronics & Optoelectronics. 2015. V. 18, N 3. P. 349-353.
Analysis of the fundamental absorption edge of the films
obtained from the C60 fullerene molecular beam in vacuum
and effect of internal mechanical stresses on it
V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 45, prospect Nauky, 03028 Kyiv, Ukraine Phone: 38 (044) 525-83-17, e-mail: matveeva@isp.kiev.ua Abstract. Nanostructures with fullerene C60 were obtained using vacuum sublimation thermal C60 fullerene powder onto unheated substrates made of silicon, mica, silica and coverslip glass. The effect of the structure, composition and mechanical stresses in the films on fundamental absorption, density-of-states tails in them were investigated by Ramаn spectroscopy, atomic force microscopy, light absorption, electroreflectance modulation spectroscopy and measuring the bend of heterosystems. Ascertained in this work has been the origin of variation observed in literature data concerning the width of the band gap Eg between 1.48 to 2.35 eV and the nature of the fundamental absorption edge in solid C60. This variation is related with decomposition of fullerene molecules caused by the increase in temperature of sublimation. It has been found that C60 in the crystalline state is direct band-gap semiconductor with Eg close to 1.6 eV in the singular point X of the Brillouin zone. The electroreflectance spectra of films and heterosystems bending were used to calculate the Eg dependence on the internal mechanical stresses. The respective coefficient value is equal to –2.8 10–10 eV/Pa. Keywords: C60 fullerene film, fundamental absorption, electroreflectance, mechanical stresses.
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