Defining how synthesis conditions of tiny crystals and wires of silicon alloys influence their structural and physical properties is the focus of a $400,000 National Science Foundation Early Career Development (CAREER) award received by Gyeong Hwang, a chemical engineer at The University of Texas at Austin.
The CAREER awards are prestigious grants for young teacher-scholars expected to be future academic leaders.
The assistant professor will use the grant to develop multiscale computational tools for exploring the synthesis, manipulation, and characterization of oxide-embedded nanocrystals and oxide-encapsulated nanowires of silicon and germanium. These silicon-germanium-oxide nanosystems are leading contenders for use in furthering the miniaturization of silicon devices below 100 nanometers, which can not be fabricated from conventional components.
Potential applications for these silicon and germanium nanostructures include serving as memory components, nanowire transistors, and as miniature optical devices to replace electronic switches. These applications should provide faster semiconductor-based devices that are cheaper and have increased functionality.
Interest in combining silicon with germanium stems from the discovery in the late 1990s that the metalloid emits light well, and has the potential for twice the speed of silicon-only transistors. However, researchers know little about controlling a nanomaterial’s function because a material’s behavior can change in unusual ways when synthesized to be as little as a billionth of a meter in size.
“Just synthesizing these silicon-germanium nanostructures and studying their physical properties after-the-fact isn’t enough,” Hwang said. “We need to first understand the underlying mechanisms of their synthesis to accurately determine their structural properties, which will in turn allows a better understanding of the relationship between their structure and properties.”
The unique properties of nanostructured materials and systems markedly depend on their size and shape. With the grant, Hwang will develop a comprehensive computational model for elucidating the fundamental formation and oxidation mechanics of silicon and germanium nanostructures and their structure-property relationships after being exposed to various process conditions and environments.
His approach involves integrating various state-of-the-art theoretical techniques that consider atomic and molecular interactions for different lengths of time and for smaller and larger clusters of atoms. The techniques include first principles Quantum Mechanics, Molecular Dynamics, Molecular Mechanics, and Monte Carlo Methods.
“Development of comprehensive computational models capable of predicting the evolution of inorganic nanostructures is an extremely challenging task because the final structure is often strongly controlled by synthesis kinetics — namely process conditions,” Hwang said.
“However, progress from this work will contribute greatly to realizing experimental control of the atomic structure and dimensionality of silicon and germanium nanostructures. It will also guide the rational design and fabrication of silicon-germanium-oxide nanosystems for future electronic and optoelectronic devices.”
For the public school outreach portion of the grant, Hwang is developing information about emerging technologies for local middle-school and high-school students of Korean descent. In connection with his research in atomistic and multiscale modeling, he is also developing teaching modules for introducing college students to the fundamental behaviors of materials and showing them how the fundamentals are linked to macroscopic phenomena associated with chemical-engineering problems.
A photo of Dr. Hwang is at: www.engr.utexas.edu/news/action_shots/pages/Hwang_2005NSFCareer.cfm
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