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

1. Hydrogen in Crystalline Semiconductors Michael Stavola, Lehigh University, DMR 0802278 The addition of a few percent N causes a surprising reduction of the band gap of the dilute III-N-V alloys like GaAs1-yNy. The further introduction of hydrogen or deuterium into these materials causes the band gap of the nitrogen-free host to be recovered. These remarkable effects caused by the interaction of N with H or D have stimulated much research on the basic physics of these materials and their application in solar cells, lasers, and novel nanostructures. A canted H-N-H (or D-N-D) defect structure has been proposed by theory as a cause of the shift of the band gap. In experiments performed by students at Lehigh Univ., the perturbation of the vibrational properties of GaAs1-yNy:D by uniaxial stress has provided an elegant experimental strategy for testing the D-N-D structure proposed by theory and for revealing rich, microscopic detail about its atomic-scale structure [1]. 1. L. Wen et al., Phys. Rev. B 81, 233201 (2010). (upper) Effect of stress on the 2217 cm-1 IR line of the D-N-D defect in GaAs1-yNy . (lower) Structure of the relaxed D-N-D defect in GaAs1-yNy.

2. Hydrogen in Crystalline Semiconductors Michael Stavola, Lehigh University, DMR 0802278 Societal Impact and Education: The research on H in semiconductors supported by NSF provides an opportunity for undergraduate and graduate 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. Highly qualified undergraduates are recruited nationwide as part of Lehigh’s Research Experiences for Under-graduates program which exposes students, often from small colleges, to university-level research Figen Bekisli, a graduate student from Lehigh Univ., and Kelsey Potter, an undergraduate student from Univ. of Tulsa, are shown making low-temperature IR absorption spectroscopy measurements to investigate the microscopic structures and properties of impurities in semiconductors.