Preventing Kinetic Roughening in Physical Vapor-Phase-Deposited Films

Abstract

The growth kinetics of the mostly used physical vapor-phase deposition techniques -molecular beam epitaxy, sputtering, flash evaporation, and pulsed laser deposition-is investigated by rate equations with the aim of testing their suitability for the preparation of ultraflat ultrathin films. The techniques are studied in regard to the roughness and morphology during early stages of growth. We demonstrate that pulsed laser deposition is the best technique for preparing the flattest films due to two key features [use of (i) a supersaturated pulsed flux of (ii) hyperthermal species] that promote a kinetically limited Ostwald ripening mechanism.

Growth kinetics of plasma-polymerized films

“…A key issue for the preparation of polymer thin films is the need to understand the growth kinetics of the film. The growth kinetics of metal or oxide thin films prepared by physical or chemical deposition methods are well known, with many studies carried out56. In the polymer thin films, Michelmore et al reported the early stage of the growth kinetics as island-like initial growth with subsequent continuous film growth7.…”

“…Thus, further application of the plasma-based deposition methods necessitates the understanding of growth kinetics in plasma-polymerized thin films. Previous reports already show that atomic force microscopy (AFM) is an excellent tool for exploring growth kinetics of film deposition as well as phase transition, etc5891011.…”

Rate equations and scaling in pulsed laser deposition

“…There is already a great amount of theoretical work on MBE [3], while there are less theoretical studies on PLD [4,5,6,7,8,9,10]. In the present paper we apply to PLD a theoretical method that proved to be very useful in MBE, namely, the rate equations approach [11].…”

Lattice relaxation of dimer islands on Ge(001) during homoepitaxy by pulsed laser deposition

“…The sudden drop in intensity of peak B during the deposition burst is related to the formation of a high density of very small islands distributed over the surface. [10,11] During the recovery time after the first deposition burst, a broad diffuse scattering background evolves into two displaced peaks E (Expanded) and C (Contracted) appearing on each side of peak B. Their integrated peak intensities without background subtraction are shown in Fig.…”

“…This relaxation behavior is evidence for ripening as has been predicted for PLD. [10] In the ripening process, small islands shrink until they disappear, while large islands grow at their expense. Similar effects have been observed for SrTiO 3 homoepitaxy during PLD by specular x-ray scattering, which is sensitive to the island size and correlations.…”