Invited Paper TF-TuM1
Atomic-Level Control of Microstructure, Morphological Evolution, and Physical Properties during Film Growth: The Golden Era of Materials Science
A primary goal of research being carried out worldwide in the area of thin film crystal growth from the vapor phase is the development of the ability to understand, control, and quantitatively model - at the atomic scale - surface chemical reaction pathways, growth kinetics, and microstructural evolution. This typically involves operating far from thermodynamic equilibrium in order to selectively open new kinetically-limited reaction paths and has resulted in the development of hybrid growth techniques which combine the inherent advantages of CVD (choice of precursor chemistries for site-specific surface reactions, self-limiting surface terminations, surface-mediated reaction kinetics, surfactant reactions, and conformal coverage), MBE (clean UHV processing compatible with in-situ surface science techniques, and low deposition temperatures), and sputter deposition (the use of hyperthermal particles to overcome surface kinetic barriers). In-situ structural (e.g., RHEED, LEED, STM, AFM) and chemical (e.g., AES, XPS, EELS, STS, TPD) probes coupled with powerful post-deposition analytical techniques such as high-resolution TEM and synchrotron-XRD, RBS, SIMS, and PL have provided the primary tools for rapid experimental progress over the past few years. The corresponding development of efficient computational methods for molecular dynamics, kinetic Monte Carlo, and density functional theory, together with powerful analytical approaches such as level-set schemes which easily handle singularities and higher dimensions, allows robust predictive modeling to proceed in parallel with experiment. Examples of atomic-scale manipulation of film chemistry, surface morphology, epitaxy by driven assembly, and preferred orientation in polycrystalline layers will be discussed. Structure and chemistry can be manipulated at all length scales from nanometer to mesoscopic to continuum through increasingly complex organizational hierarchies.