title: Enhanced NMR with Optical Pumping Yields75As Signals Selectively from a Buried GaAs Interface.
abstract: We have measured the75As signals arising from the interface region of single-crystal semi-insulating GaAs that has been coated and passivated with an aluminum oxide film deposited by atomic layer deposition (ALD) with optically pumped NMR (OPNMR). Using wavelength-selective optical pumping, the laser restricts the volume from which OPNMR signals are collected. Here, OPNMR signals were obtained from the interface region and distinguished from signals arising from the bulk. The interface region is highlighted by interactions that disrupt the cubic symmetry of the GaAs lattice, resulting in quadrupolar satellites for nuclear [Formula: see text] isotopes, whereas NMR of the "bulk" lattice is nominally unsplit. Quadrupolar splitting at the interface arises from strain based on lattice mismatch between the GaAs and ALD-deposited aluminum oxide due to their different coefficients of thermal expansion. Such spectroscopic evidence of strain can be useful for measuring lattice distortions at heterojunction boundaries and interfaces.
authors.affiliation: Department of Chemistry, Washington University , Saint Louis, Missouri 63130, United States.
authors.forename: Matthew M
authors.initials: MM
authors.lastname: Willmering
authors.affiliation: Department of Chemistry, Washington University , Saint Louis, Missouri 63130, United States.
authors.forename: Zayd L
authors.initials: ZL
authors.lastname: Ma
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Jenkins
authors.affiliation: School of Electrical Engineering and Computer Science, Oregon State University , Corvallis, Oregon 97331, United States.
authors.forename: John F
authors.initials: JF
authors.lastname: Conley
authors.affiliation: Department of Chemistry, Washington University , Saint Louis, Missouri 63130, United States.
authors.forename: Sophia E
authors.identifier: 0000-0002-2809-6193
authors.initials: SE
authors.lastname: Hayes