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HL: Halbleiterphysik

HL 23: Poster II

HL 23.65: Poster

Mittwoch, 24. März 1999, 14:00–18:00, Z

Formation of PTCDA films by Pulsed Laser Deposition — •N. Kochan, N. Vogel, T.U. Kampen, A.G. Milekhin, and D.R.T. Zahn — Institut f"ur Physik, Technische Universit"at, D-09107 Chemnitz

Thin semiconducting organic films of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) were prepared by Nd:YAG laser ablation from a PTCDA pellet. Hydrogen passivated Si(111) served as substrate. The laser wavelengths used were 1064 nm, 532 nm, and 355 nm with a pulse duration of 100 ps. The deposited films were investigated by Raman spectroscopy and scanning electron microscopy (SEM).

While SEM images reveal a decrease in particle size with decreasing laser wavelength, Raman scattering experiments allow the determination of the composition of the organic films. Films prepared using a wavelength 1064 nm and 355 nm show the A_1g vibrational modes of the PTCDA molecule. The 532 nm line lies in the absorption maximum of PTCDA, and the films ablated using this wavelength show a broadening of the spectral features as well as a shift to lower frequencies. The observed spectra are thus typical for the polymer polyperinaphthalene (PPN) which is formed during the ablation process.