Microwave-assisted Synthesis of Germanium Nanocrystals: Crystal Growth and Composition

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Susan M. Kauzlarich of the University of California Davis aims to advance and expand the chemistry of germanium semiconductor nanocrystals. Doped and alloyed germanium semiconductor nanoparticles will be prepared with microwave heating to provide insights into size, shape, and surface control. Diamond-structured germanium uniquely absorbs microwave radiation, providing local heating and crystalline nanoparticles at lower temperatures than convection heating. The combination of elements such as aluminum, gallium, indium, and phosphorus with germanium is expected to change the properties of the nanoparticles. The research aims to advance chemical knowledge enabling the synthesis of high quality nanoparticles with specific properties. The research will also serve to train members of the next generation of scientists in the chemistry of semiconductors. These early career scientists will present their findings to the community through publications and presentations, to disseminate their work. New teaching materials for chemistry courses to help students learn about these new approaches to nanomaterial synthesis and to the study of nanomaterial properties will be developed and assessed. New learning materials related on main group semiconductor chemistry will be developed, assessed, and shared with the broader community in collaboration with the Interactive Online Network of Inorganic Chemists (IONiC). Control over the chemistry of semiconductor nanoparticles is essential for energy conversion applications. This project, with the support of the Macromolecular, Supramolecular, and Nanochemistry Program in the Division of Chemistry, will provide new doped and alloyed germanium semiconductor nanocrystals and investigate the influence of Brønsted bases on their size, shape, and yield. Utilizing a microwave-assisted synthetic approach, the reduction of germanium halides in amine solvents will be explored to achieve highly crystalline products at moderate temperatures. Various Brønsted bases with different pKa values will be studied to discern their roles in nanoparticle formation processes including ligand coordination, nucleation, and growth. Incorporating p-type and n-type dopants into Ge will be investigated, as will surface capping and shell formation, as approaches to mitigating surface defects. The impact of these design elements on the optoelectronic properties of the resulting nanocrystals will be analyzed. If successful, this research has the potential to provide access to semiconductor nanoparticles with both innovative structures and useful properties, an area of great significance in fundamental science and engineering with potentially broad scientific and technological impact. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.