Preventing kinetic roughening in physical vapor-phase-deposited films

Growth kinetics of plasma-polymerized films

The growth kinetics of polymer thin films prepared by plasma-based deposition method were explored using atomic force microscopy. The growth behavior of the first layer of the polythiophene somewhat differs from that of the other layers because the first layer is directly deposited on the substrate, whereas the other layers are deposited on the polymer itself. After the deposition of the first layer, each layer is formed with a cycle of 15 s. The present work represents the growth kinetics of the plasma-polymerized films and could be helpful for further studies on growth kinetics in other material systems as well as for applications of plasma-polymerized thin films.

Reducing the surface roughness beyond the pulsed-laser-deposition limit

Here, we outline the theoretical fundamentals of a promising growth kinetics of films from the vapor phase, in which pulsed fluxes are combined with temperature transients to enable short-range surface relaxations (e.g., species rearrangements) and to inhibit long-range relaxations (atomic exchange between species). A group of physical techniques (fully pulsed thermal and/or laser depositions) based on this kinetics is developed that can be used to prepare films with roughnesses even lower than those obtained with pulsed-laser deposition, which is the physical vapor-phase deposition technique that has produced the flattest films reported so far.

Rate equations and scaling in pulsed laser deposition

We study a simplified model for pulsed laser deposition [Hinnemann, Phys. Rev. Lett. 87, 135701 (2001)] by rate equations. We consider a set of equations where islands are assumed to be pointlike, as well as an improved one that takes the size of the islands into account. The first set of equations is solved exactly but its predictive power is restricted to a few pulses. The improved set of equations is integrated numerically, is in excellent agreement with simulations, and fully accounts for the crossover from continuous to pulsed deposition. Moreover, we analyze the scaling of the nucleation density and show numerical results indicating that a previously observed logarithmic scaling does not apply.