Hydrogen in Transparent Conducting Oxides

Lehigh University, Bethlehem PA

Investigators

Abstract

****Technical Abstract**** The physics of hydrogen impurities in transparent conducting oxides, a rapidly emerging class of electronic materials, is the focus of this research program. The transparent conducting oxides combine transparency in the visible with high conductivity. Native defects such as oxygen vacancies and cation interstitials have traditionally been invoked as the source of conductivity. Recent theory, however, finds that in many conducting oxides, native defects are unlikely to be responsible for their conductivity. Instead, hydrogen centers are predicted to be shallow donors that give rise to strong n-type behavior. While a number of exciting theoretical predictions have been made, a modern understanding of the conductivity of transparent conducting oxides and the role played by hydrogen is in its infancy. IR and Raman spectroscopies will be used to probe the structures and reactions of H-related centers and their relationship to changes in conductivity. A central goal of this project is the education of students. Experimental studies of impurities and defects in semiconducting oxides and their effect on conductivity provide an excellent opportunity for students to learn about the optical properties of materials, characterization methods, and how defects affect properties. Students are engaged in collaborations with leading research groups in the U.S. and abroad and learn the value of teamwork by first-hand experience. ****Non-Technical Abstract**** The focus of this research program is an experimental study of hydrogen in transparent conducting oxides, an unusual class of materials that combine transparency in the visible with high conductivity. Transparent conducting oxides are widely used in common electronic devices like flat-panel displays for computers. The presence of hydrogen is common in the metal oxides where it forms strong O-H bonds and interacts with other impurities and defects. Surprisingly, hydrogen is proposed to be an important source of conductivity. The goal of this project is a fundamental understanding of the hydrogen impurity in conducting oxides, its fascinating reaction chemistry, and hydrogen's role as a source of conductivity. Research on strategic electronic materials, where interesting physics and important technological applications intersect, provides students with an excellent opportunity to learn about current developments in semiconductor technology, the optical properties of materials, the physics of semiconductors, and how defects affect properties. And the opportunity for a student to make important contributions to problems that have an impact on electronics technology ignites in him or her the excitement that leads to a successful career in science and engineering.