Stochastic analysis on temperature-dependent roughening of amorphous organic films

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.