Hydrogen in Crystalline Semiconductors Michael J. Stavola, Lehigh University, DMR 0802278

1. Hydrogen in Crystalline Semiconductors Michael J. Stavola, Lehigh University, DMR 0802278 Hydrogen in transparent conducting oxides: Transparent conducting oxides are unusual but highly useful materials that combine transparency in the visible with the high conductivity of metals. The transparent conductor SnO2 has attracted much recent attention. Traditionally, oxygen vacancies and tin interstitials were thought to be the cause of conductivity. However, recent theory has suggested that the conductivity of SnO2 is due,instead, to hydrogen impurities. The properties of H in SnO2 single crystals have been studied with infrared spectroscopy. When H is introduced into SnO2, several O-H vibrational lines are produced along with the low-frequency absorption that is characteristic of free carriers. Centers containing H have been associated with shallow donors in SnO2 that give rise to strong n-type conductivity and with defects in which H is bonded to interstitial Sn atoms. (upper) Polarization dependence of the IR spectrum of SnO2 treated in an H2 ambient. (lower) Structure of an (O-H)2 center in which two H atoms are bonded near an interstitial Sn atom. The blue atoms are oxygen, the black atoms are tin. H ISn H

2. Hydrogen in Crystalline Semiconductors Michael J. Stavola, Lehigh University, DMR 0802278 Societal Impact and Education: Our research on hydrogen in semiconductors provides an opportunity for students to make important contributions to problems in semi-conductor physics that have an impact on electronics technology, often in collaboration with leading scientists in the US and abroad. This experience helps to ignite in students the excitement that leads to successful careers in science. Three recent Ph.D. graduates have joined the energy industry in the US. We are proud of our success with the education of women in physics. Over the past decade, 80% of the students educated in this research program are women. Highly qualified undergraduates are recruited nationwide as part of Lehigh’s Research Experiences for Undergraduates program which exposes students, often from small colleges, to university-level research. Figen Bekisli and Lanlin Wen, graduate students at Lehigh University, and Kelsey Potter, an undergraduate student from the University of Tulsa, are shown making low-temperature, IR-absorption spectroscopy measurements to investigate the microscopic structures and properties of impurities in semiconductors.