Light Scattering from Strongly Perturbed Semiconductors

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This research project is developing a new technique, based on the detection of interface elastic waves by Brillouin scattering, to measure the bulk elastic constants of solids under hundreds of kilobars of hydrostatic pressure. This unique capability will permit the investigation of the almost universal softening of acoustic phonons with pressure in cubic semiconductors and their potential role in structural phase transitions. Measurements on semiconductor alloys and heterostructures will allow isolation of compositional and interfacial strain effects. Resonant Raman scattering will be employed to study the exchange-mediated phonon renormalization discovered in cobalt-based dilute magnetic semiconductors. Antoher program on II-V semiconductors is attempting to elucidate the fundamental driving mechanism for their novel ordering during epitaxial growth and to explore the possibility to stabilize through strain otherwise unstable crystal lattices.