W. Alan Doolittle - Creative Epitaxy: Finding Ways to Violate Assumptions that Breach Material Barriers
From Katie Gentilello
Epitaxial processes are considered routine for applications spanning established industries from the silicon and GaN semiconductor industries to cutting edge research. As many as 10,000 epitaxial reactors crank out billions of dollars’ worth of light emitting diode chips for solid state white lighting alone. Those metrics increase 100-fold for silicon applications. Epitaxy is core to countless industries but is mostly performed in ways that have not changed for decades. But epitaxy can also be performed in non-standard ways to overcome “perceived” barriers to materials synthesis. Several examples will be given in this talk including: 1) Dynamic control of surface chemistry so as to enable higher solubility of desirable impurities; 2) Dynamic control of surface energy facilitating 3D control of alloy composition and material properties; 3) Electrothermal control of epitaxy to enable metastable phase materials; And 4) the “invention” of the widest semiconductor known. Each of these example problems has been solved by a common “thought process” wherein the fundamental assumption behind the limitation was defined and ways of violating the identified assumption was explored leading to new functionality in materials. The importance of the process – assumption identification and violation – will be discussed in hopes of conveying an important approach to solving hard problems. New emerging industries such as optoelectronics, neuromorphic computing and power electronics will be highlighted as beneficiaries of these unique approaches.