Characterization and Control of Interfacial Structure in Type-II Superlattices and Quantum Wells

Texas A&M Research Foundation, College Station TX

Investigators

Abstract

This project addresses atomic-scale characterization and control of interface structure and composition in type-II quantum wells and superlattices grown by molecular-beam (MBE), and migration-enhanced (MEE), epitaxy. The approach emphasizes cross-sectional scanning tunneling microscopy (STM), examining limitations to interfacial perfection imposed by anion and cation segregation, incomplete bond type selectivity, and kinetically limited surface roughness, under a variety of growth conditions. Complete deconvolution of the respective roles of interface morphology (due to islanding in the growth plane) and inhomogeneous composition (due to mixed interface bond types, cross incorporation, or segregation) on interface roughness is expected. Characterization will be used to identify and understand growth conditions and associated phenomena which afford maximal control over interface bonding and planarity. Accordingly it is anticipated that structural and composition perfection needed for optimal type-II quantum well devices may be better understood, controlled and realized. %%% The project addresses basic research issues in a topical area of materials science with high technological relevance. Experimental tools are now available to allow atomic level observation of elementary surface processes which when better understood allow advances in fundamental science and technology. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. ***