Characterization Of Epitaxial Semiconductor Films

The characterization of epitaxial layers and their surfaces has benefitted a lot from the enormous progress of optical analysis techniques during the last decade. In particular, the dramatic improvement of the structural quality of semiconductor epilayers and heterostructures results to a great deal from the level of sophistication achieved with such analysis techniques. First of all, optical techniques are nondestructive and their sensitivity has been improved to such an extent that nowadays the epilayer analysis can be performed on layers with thicknesses on the atomic scale. Furthermore, the spatial and temporal resolution have been pushed to such limits that real time observation of surface processes during epitaxial growth is possible with techniques like reflectance difference spectroscopy. Of course, optical spectroscopies complement techniques based on the inter action of electrons with matter, but whereas the latter usually require high or ultrahigh vacuum conditions, the former ones can be applied in different environments as well. This advantage could turn out extremely important for a rather technological point of view, i.e. for the surveillance of modern semiconductor processes. Despite the large potential of techniques based on the interaction of electromagnetic waves with surfaces and epilayers, optical techniques are apparently moving only slowly into this area of technology. One reason for this might be that some prejudices still exist regarding their sensitivity.

Heteroepitaxy has evolved rapidly in recent years. With each new wave of material/substrate combinations, our understanding of how to control crystal growth becomes more refined. Most books on the subject focus on a specific material or material family, narrowly explaining the processes and techniques appropriate for each. Surveying the principles common to all types of semiconductor materials, Heteroepitaxy of Semiconductors: Theory, Growth, and Characterization is the first comprehensive, fundamental introduction to the field. This book reflects our current understanding of nucleation, growth modes, relaxation of strained layers, and dislocation dynamics without emphasizing any particular material. Following an overview of the properties of semiconductors, the author introduces the important heteroepitaxial growth methods and provides a survey of semiconductor crystal surfaces, their structures, and nucleation. With this foundation, the book provides in-depth descriptions of mismatched heteroepitaxy and lattice strain relaxation, various characterization tools used to monitor and evaluate the growth process, and finally, defect engineering approaches. Numerous examples highlight the concepts while extensive micrographs, schematics of experimental setups, and graphs illustrate the discussion. Serving as a solid starting point for this rapidly evolving area, Heteroepitaxy of Semiconductors: Theory, Growth, and Characterization makes the principles of heteroepitaxy easily accessible to anyone preparing to enter the field.

This volume is devoted to the consideration of the use use of surface, thin film and interface characterization tools in support of silicon-based semiconductor processing. The approach taken is to consider each of the types of films used in silicon devices individually in its own chapter and to discuss typical problems seen throughout that films' history, including characterization tools which are most effectively used to clarifying and solving those problems.

This subject is divided into two volumes. Volume I is on homoepitaxy with the necessary systems, techniques, and models for growth and dopant incorporation. Three chapters on homoepitaxy are followed by two chapters describing the different ways in which MBE may be applied to create insulator/Si stackings which may be used for three-dimensional circuits. The two remaining chapters in Volume I are devoted to device applications. The first three chapters of Volume II treat all aspects of heteroepitaxy with the exception of the epitaxial insulator/Si structures already treated in volume I.

Some years ago it was not uncommon for materials scientists, even within the electronics industry, to work relatively independently of device engi neers. Neither group had a means to determine whether or not the materials had been optimized for application in specific device structures. This mode of operation is no longer desirable or possible. The introduction of a new material, or a new form of a well known material, now requires a close collaborative effort between individuals who represent the disciplines of materials preparation, materials characterization, device design and pro cessing, and the analysis of the device operation to establish relationships between device performance and the materials properties. The develop ment of devices in heteroepitaxial thin films has advanced to the present state specifically through the unusually close and active interchange among individuals with the appropriate backgrounds. We find no book available which brings together a description of these diverse disciplines needed for the development of such a materials-device technology. Therefore, the authors of this book, who have worked in close collaboration for a number of years, were motivated to collect their experiences in this volume. Over the years there has been a logical flow of activity beginning with heteroepi taxial silicon and progressing through the III-V and II-VI compounds. For each material the early emphasis on material preparation and characteriza tion later shifted to an emphasis on the analysis of the device characteristics specific to the materials involved.