CAREER: Band Engineering in Amorphous Semiconductors

Regents Of The University Of Michigan - Ann Arbor, Ann Arbor MI

Investigators

Abstract

Non-Technical Description: At the core of today?s electronics are semiconductor materials. The optical energy at which a semiconductor strongly absorbs light is known as its bandgap. By mixing two different materials to form a semiconductor alloy, its bandgap can be tuned. The first goal of this project is to study the fundamental materials properties and bandgap tuning in alloys made of amorphous, or disordered, oxide semiconductors. These wide bandgap materials are less explored but very promising for applications of strong societal importance such as devices for renewable energy and health care. The second goal of this project is to bring together research and education by engaging the entire research team in outreach activities with the public, including school-age learners. In addition, the principal investigator provides mentoring to graduate and undergraduate students through research activities and ?Career Connections? events featuring discussions with practicing scientists and engineers. Technical Description: This project explores band engineering of amorphous oxide semiconductor thin films via quaternary and quinary alloying. These materials have a wide bandgap, similar to that of gallium nitride. Multi-component phase diagrams are used to relate oxide alloy composition to thermodynamic stability and materials properties. The specific objectives of this project are: (i) to investigate the alloy composition ranges and thermodynamic pathways available for meta-stable band-engineered amorphous alloy films; (ii) to characterize charge transport and sub-bandgap density of states as a function of alloy composition, using electrical and opto-electronic techniques; (iii) to develop models and experimentally validate hetero-structure interface formation in amorphous oxide alloys. Through these studies, this project significantly expands the present scientific understanding and application scope of disordered semiconductors. Heterostructures made using these band-engineered amorphous oxide alloys can be used in future high-power electronics or deep ultraviolet optoelectronics devices.