This Materials World Network collaborative proposal from Kansas State University and State University of New York at Stony Brook is to study the properties of the boron-rich icosahedral semiconductors B12As2 and B4C lie at the extremes in many categories including high melting temperatures, hardness, resistance to radiation damage, and Seebeck coefficients. Enhancements of these properties may be realized by combining these materials together to create compositional heterostructures. The main objectives of this research are: (a) to develop process conditions capable of producing single and multiple thin layers combining both materials with controlled stoichiometry and impurity concentrations by chemical vapor deposition; (b) to identify the types and density of crystalline defects present in both the bulk of the thin films and those caused by interfaces between materials; and (c) to investigate the electrical, optical, and thermal properties of base semiconductors and their composite structures. This award supports collaboration between Kansas State University (film growth), SUNY-SB (synchrotron, TEM characterization) and Bristol University (Raman, optical and ellipsometric characterization) on the synthesis of films of B12As2 and B4C and their subsequent characterization using a range of structural and spectroscopic methods. The compositional limits to deviations from stoichiometry and their effects on the mechanical and thermal properties will also be studied. During exchanges between institutes, students will learn the capabilities and limitations of the materials synthesis and characterization techniques, and to appreciate the context of their work in the project as a whole. The outreach programs supported by this award will build on existing efforts and should offer opportunities for better exposure to materials research for students.
This study will establish the relationship between the processing, structure, composition, and properties of these boride semiconductors, so their potential applications as high temperature electronics, thermo electronics, radiation sensors and other devices may be realized. The students involved in this research will receive an educational experience, which is both broad and in depth including fundamental aspects of crystal growth, epitaxy, materials characterization, and materials property engineering. Their educational experience will benefit from exchange visits between the institutes involved, fieldwork at national laboratories, and interactions with experts in this field, presentations of their research at professional meetings, and presentations to the general public. A new educational outreach program will be initiated for middle school students for which English is a second language. Its goal is to stimulate student interest in science and engineering through hands-on activities and demonstrations on crystal growth and the applications of semiconductors.
