Anomalous scaling behavior and surface roughening in molecular thin-film deposition

Abstract

The thin film growth dynamics of a molecular semiconductor, free-base phthalocyanine $({\mathrm{H}}_{2}\mathrm{Pc})$, deposited by organic molecular beam deposition, has been studied by atomic force microscopy (AFM) and height difference correlation function (HDCF) analysis. The measured dynamic scaling components (${\ensuremath{\alpha}}_{\mathit{loc}}=0.61\ifmmode\pm\else\textpm\fi{}0.12$, $\ensuremath{\beta}=1.02\ifmmode\pm\else\textpm\fi{}0.08$, and $1∕z=0.72\ifmmode\pm\else\textpm\fi{}0.13$) are consistent with rapid surface roughening and anomalous scaling behavior. A detailed analysis of AFM images and simple growth models suggest that this behavior arises from the pronounced upward growth of crystalline ${\mathrm{H}}_{2}\mathrm{Pc}$ mounds during the initial stages of thin film growth.