Stochastic analysis on temperature-dependent roughening of amorphous organic films

¹  Institute of Physics (IA), RWTH Aachen University of Technology - 52056 Aachen, Germany
²  AIXTRON AG - Kackertstr. 15-17, D-52072 Aachen, Germany
³  Institute of Theoretical Physics, University of Münster - D-48149 Münster, Germany
⁴  Fachbereich Physik, Universität Osnabrück - Barbarastraße, D-49076 Osnabrück, Germany
⁵  Institute of Physics II, University of Cologne - Zülpicherstr. 77, D-50937, Cologne, Germany

Corresponding author: farahzadi@physik.rwth-aachen.de

Received: 25 September 2009
Accepted: 23 March 2010

Abstract

We investigate the temperature- and flux-dependent roughening of amorphous organic thin films of N,N'-diphenyl-N,N'-bis(1-naphthyl)-1-1'biphenyl-4,4''diamine (α-NPD) molecules grown by organic vapor phase deposition. We find that organic thin films become unstable at high temperatures and low deposition rates as well as at low temperatures and high deposition rates. Based on a detailed stochastic analysis of the morphology we suggest probable mechanism for the roughening phenomena. Indeed, this result allows us to identify the optimum deposition conditions for relevant technological applications.