Regensburg 2002 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 21: Organische Halbleiter

HL 21.2: Vortrag

Dienstag, 12. März 2002, 14:45–15:00, H17

Influence of substrate temperature on organic films studied by XRD, XXR and AFM — •A. Das, G. Salvan, T.U. Kampen, and D.R.T. Zahn — Institut for Halbleiterphysik, Technische Universit*t Chemnitz, D-09107 Germany

X-ray diffraction, X-ray reflectivity(XRR), and atomic force microscopy were used to study the structural order of thin films of 3,4,9,10-perylene tetracarboxylic dianhydride (PTCDA). The PTCDA films were grown by organic molecular beam deposition (OMBD) under UHV conditions on hydrogen passivated p-type silicon (100) substrates. The substrate temperatures were varied from 230 K to 410 K. All these films show an quasi-epitaxial growth of PTCDA. A peak corresponding to the (102) X-ray diffraction plane of the monoclinic structure of crystalliunity PTCDA is observed at 2 theta = 27.65 degree. Further analysis of the diffraction data clearly shows an enhancement of the crystallinity of the PTCDA films with increasing substrate temperature. The full width at half maximum (FWHM) of the diffracted peak is found to decrease with increasing temperature and the grain sizes of the deposited films increase from   45 nm at 230 K to   70 nm at 410 K. X-ray reflectivity is employed to understand the effect of increasing substrate temperature on the surface and interface roughness. The surface and interface roughness measured by XRR are in agreement with the data obtained from atomic force microscopy measurements.