Research On Growth And Spectra Character Of Pentacene Thin Film

In recent years, organic semiconductor materials have attracted great interests and its performance has been improved drastically because of its low cost and simple processing. Though there are a lot of organic semiconductor materials, pentacene is one kind of the most important materials because of it's high carrier mobilities and excellent crystalline quality. OFET fabricated by pentacene has a high mobility which can be compared with that of Amorphous silicon.Optimization of the organic crystal fabrication process is important to obtain high performance of organic semiconductor devices such as organic field-effect transistors (OFETs). In this paper, the thin-films of organic semiconductor pentacene were fabricated by thermal evaporation on silicon substrates coated with SiO2 layer by dry oxidation. X-ray diffraction (XRD) patterns, atomic force microscopic images and Raman scatter spectrum were employed to analyze the surface morphologies and crystal structures of the samples. The influences of different substrate temperatures on the crystallization were explored and the thin films with good crystal quality were obtained. By the measurement of time-of-flight (TOF), we obtained the estimated value of the charge carrier drift mobility(μ) which was about 10-3cm2V-1s-1.UV-Visible absorption spectrum and photoluminescence (PL) spectrum of pentacene film were also analyzed. We assigned the main reasons of the peaks of these two spectra, especially taking emphases on the influence of Davydov splitting.