The purpose of this article is to describe the basic physical processes involved in the nucleation and growth of thin films of materials on solid surfaces. In this introduction the three modes of crystal growth which are thought to occur on surfaces in the absence of interdiffusion are described, and the relationships between the thermodynamics of adsorption and the kinetics of crystal growth are explored in general terms. This is followed by a brief review of atomistic nucleation theory, explaining the relations of such theories to experimental observables. In the next three sections, recent experimental examples of these three growth modes are given, which are interpreted where possible in terms of nucleation and growth theory. The last section discusses observations on the shapes of growing crystallites and the relation of such observations to nucleation and surface diffusion processes.

https://iopscience.iop.org/article/10.1088/0034-4885/47/4/002/pdf

Nucleation and growth of thin films

Materials research plays a vital role in transforming breakthrough scientific ideas into next-generation technology. Similar to the way silicon revolutionized the microelectronics industry, the proper materials can greatly impact the field of plasmonics and metamaterials. Currently, research in plasmonics and metamaterials lacks good material building blocks in order to realize useful devices. Such devices suffer from many drawbacks arising from the undesirable properties of their material building blocks, especially metals. There are many materials, other than conventional metallic components such as gold and silver, that exhibit metallic properties and provide advantages in device performance, design flexibility, fabrication, integration, and tunability. This review explores different material classes for plasmonic and metamaterial applications, such as conventional semiconductors, transparent conducting oxides, perovskite oxides, metal nitrides, silicides, germanides, and 2D materials such as graphene. This review provides a summary of the recent developments in the search for better plasmonic materials and an outlook of further research directions.

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Alternative Plasmonic Materials: Beyond Gold and Silver

During the past decade, enormous progress has been made in growing ultrathin organic films and multilayer structures with a wide range of exciting optoelectronic properties. This progress has been made possible by several important advances in our understanding of organic films and their modes of growth. Perhaps the single most important advance has been the use of ultrahigh vacuum (UHV) as a means to achieve, for the first time, monolayer control over the growth of organic thin films with extremely high chemical purity and structural precision.1-3 Such monolayer control has been possible for many years using well-known techniques such as Langmuir-Blodgett film deposition,4 and more recently, self-assembled monolayers from solution have also been achieved.5 However, ultrahighvacuum growth, sometimes referred to as organic molecular beam deposition (OMBD) or organic molecular beam epitaxy (OMBE), has the advantage of providing both layer thickness control and an atomically clean environment and substrate. When combined with the ability to perform in situ highresolution structural diagnostics of the films as they are being deposited, techniques such as OMBD have provided an entirely new prospect for understanding many of the fundamental structural and optoelectronic properties of ultrathin organic film systems. Since such systems are both of intrinsic as well as practical interest, substantial effort worldwide has been invested in attempting to grow and investigate the properties of such thin-film systems. This paper is a review of recent progress made in organic thin films grown in ultrahigh vacuum or using other vapor-phase deposition methods. We will describe the most important work which has been published in this field since the emergence of OMBD in the mid-1980s. Both the nature of thin-film growth and structural ordering will be discussed, as well as some of the more interesting consequences to the physical properties of such organic thin-film systems will be considered both from a theoretical as well as an experimental viewpoint. Indeed, it will 1793 Chem. Rev. 1997, 97, 1793−1896

Ultrathin Organic Films Grown by Organic Molecular Beam Deposition and Related Techniques.

Detailed observations have been made of the intensity oscillations in the specularly reflected and various diffracted beams in the RHEED pattern during MBE growth of GaAs, Ga
 x
 Al1−x
As and Ge. The results indicate that growth occurs predominantly in a two-dimensional layer-by-layer mode, but there is some roughening, which is enhanced by deviations from stoichiometry and the presence of impurities. In the case of the GaAs (001) −2×4 reconstructed surface a combination of dynamic and static RHEED measurements has provided firm evidence for the presence of one-dimensional disorder features as well as surface steps.

Dynamics of film growth of GaAs by MBE from Rheed observations

This review describes recent progress in the understanding of the emergence of scale invariance in far-from-equilibrium growth. The first section is devoted to ‘solvable’ needle models which illustrate the relationship between long-range competition mediated, for example, through shadowing or a Laplacian field, and scale invariance. The following three sections, which comprise the bulk of the article, develop the theory of kinetic surface roughening in a comprehensive manner. The two large classes of kinetic roughening processes, characterized by non-conserved (Kardar-Parisi-Zhang) and conserved (ideal molecular beam epitaxy (MBE)) surface relaxation, respectively, are treated separately. For the former case, which has been extensively reviewed elsewhere, the focus is on recent developments. For the case of ideal MBE we give a systematic derivation of the various universality classes in terms of microscopic processes, and compare the predictions of continuum theory to computer simulations and exp...

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Origins of scale invariance in growth processes

A simple extension of the reflection high‐energy electron diffraction oscillation technique to vicinal surfaces provides a means of studying surface diffusion during molecular beam epitaxial growth. The basis of the method is described and some preliminary results for Ga diffusion during the growth of GaAs films with (001) 2×4 and 3×1 reconstructed surfaces are presented.

Reflection high‐energy electron diffraction oscillations from vicinal surfaces—a new approach to surface diffusion measurements

Detailed measurements have been made of the specular beam intensity in RHEED patterns from static and growing GaAs surfaces. The basic parameters investigated were substrate temperature and electron beam azimuth. The results have provided further understanding of growth dynamics and surface disorder, respectively. There is a significant trend away from two-dimensional growth at the higher temperatures, which also correspond to more Ga-rich surface structures. Conversely, surface disorder is apparently greater during growth at the lower temperatures, where the structure is As-rich. The static As-stable 2×4 surface is, however, the most ordered and the most closely two-dimensional. It has also been shown that ordered, two-dimensional growth can be initiated from excess Ga adatom populations.

J.H. Neave

Papers

Dynamics of film growth of GaAs by MBE from Rheed observations

Reflection high‐energy electron diffraction oscillations from vicinal surfaces—a new approach to surface diffusion measurements

Dynamic RHEED observations of the MBE growth of GaAs

Rheed studies of heterojunction and quantum well formation during MBE growth-from multiple scattering to band offsets

Structure and stoichiometry of {100} GaAs surfaces during molecular beam epitaxy