Raman monitoring of organic semiconductor heterostructure formation

The growth of perylene-3,4,9,10-tetracarboxylic dianhydrid (PTCDA) was monitored by Raman spectroscopy. Organic molecular beam deposition (OMBD) was used to evaporate PTCDA on hydrogen-passivated Si(111) and selenium-passivated GaAs(100) surfaces. The frequency positions and intensities of the most pronounced Raman lines are analyzed on the basis of density functional tight-binding calculations (DFTB). Spectra were also taken from PTCDA single crystals and used to determine the structural quality of the PTCDA films.