Atomic-Scale Structures and Properties of Hydrogen-Containing Defects in Semiconductors

Lehigh University, Bethlehem PA

Investigators

Abstract

Hydrogen is an important impurity in semiconductors because of its fascinating fundamental properties and its impact on semiconductor technology. Hydrogen is introduced easily into semiconductors, either intentionally or unintentionally, where it interacts strongly with other impurities and defects. Hydrogen plays a multifaceted role where it can passivate shallow impurities, eliminate deleterious properties of deep-level defects, and, in some cases, act as an unintentional dopant or even modify the bandgap of the host crystal. This project focuses on new experiments aimed at providing structure-sensitive data for interstitial H2 in Si, elucidating the interaction of H with native defects in Si, and studying H in III-N-V alloys and in wide-band-gap semiconductors. Vibrational spectroscopy of the light H atom has proved to be an excellent probe of H-containing defects and is the principal method to be used to determine microscopic properties. The experimental work on H in semiconductors conducted in this program provides an excellent means to educate undergraduate and graduate students in semiconductor physics. Students learn about the physics of electronic materials, crystal defects, and the optical properties of materials, providing a strong foundation for careers in education or industrial R&D. Although hydrogen is the simplest atom, it is a complicated impurity in semiconductors with properties that have fascinated defect specialists. Furthermore, H is ubiquitous in the semiconductor growth and processing environment and is introduced easily into semiconductors. Once present, H modifies the electrical properties of semiconductor materials and the behavior of electronic devices. Experimental studies of the atomic-scale structures of hydrogen-containing defects in semiconductors are the focus of this research program. The absorption of infrared light by the vibrational motion of the light H atom is used to probe microscopic properties. The semiconductor materials of interest include Si, which is important for integrated circuits and solar cells, and compound semiconductors that are important for light-emitting devices. This experimental program on H in semiconductors provides an excellent opportunity for undergraduate and graduate students to learn about the semiconductor materials that are important for electronic device technology. 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.