Effects of applied pressure on phonon and electron states in solids
High pressure structural phase-transitions in tetrahedral semiconductors
Pressure-induced deep defects, disorder, and electron localization in crystals
Photo-induced crystallization in amorphous Se and chalcogenide glasses
Anharmonic resonant phonon interactions in semiconductors
Studies of the above phenomena by Raman scattering, other spectral probes, and by novel diamond-anvil cell high pressure experiments

Professor Weinstein's research interests are in experimental studies of the optical and high-pressure physics of solids. Raman scattering, luminescence, and other visible/infrared spectroscopies are focused on the phonon and electron excitations in semiconductor crystals, alloys, nanostructures, and glasses. Diamond-anvil cells are employed to probe the hydrostatic- pressure dependence of these excitations and the structural phase transitions in the materials. The most recent studies by Weinstein’s group have explored: correlation between pressure-softening of TA phonons and phase changes, pressure effects in the novel perovskite BaZrS3, and precipitate formation and plasticity under applied pressure in II-VI crystals. (See Selected Publications below.)

Earlier work by Weinstein on phonons, anharmonic interactions, and phase changes in Group IV, III-V, and II-VI crystals led to an understanding of the effects of pressure on the dispersion of optic- and acoustic- branches in these materials across the Brillouin Zone. Subsequent research on the high-pressure phase changes in epitaxial multilayers revealed superpressing behavior that bears on the growth (at 1 atm.) of metastable strained-layer systems. Studies of intrinsic and defect electron states explored how applied pressure tunes the extended-localized nature of impurities in n-type ZnSe and of N-pairs in GaAs1-xNx, and how pressure enhances the lattice relaxation of Zn-vacancies in ZnS. Another area of Weinstein’s interest has been the properties of chalcogenide glasses at both ambient and elevated pressures. Experiments on amorphous Se films show that photo-crystallization is promoted by as-grown interface strain, and studies on several As- and Ge- chalcogenide glasses and crystals find connections between the network dimensionality of bonding and photoelastic behavior.

Professor Weinstein has made significant contributions to high-pressure experimentation by pioneering the use of the modern diamond-anvil cell for Raman scattering and other optical studies. He also advanced cryogenic pressure research, developing tunable low-temperature diamond-anvil cells, including an apparatus patented with R. J. Chen for far infrared magnetospectroscopy.

Selected Publications

“Pressure-softening of zone-edge TA phonons and the fourfold to sixfold phase change”, B. A. Weinstein, Phys. Rev. B 104, 054105-(1-8), (2021).
“Stability and Band-Gap Tuning of the Chalcogenide Perovskite BaZrS3 in Raman and Optical Investigations at High Pressures”, Nelson Gross, Yi-Yang Sun, Samanthe Perera, Haolei Hui, Xiucheng Wei, Shengbai Zhang, Hao Zeng, B. A. Weinstein, Phys. Rev. Applied 8, 044014 (2017).
“Precipitation of anion inclusions and plasticity under hydrostatic pressure in II-VI crystals”, G. P. Lindberg and B. A. Weinstein, Phys. Rev. B 94, 134102-(1-18), (2016).
“Photo-crystallization in a-Se layer structures: Effects of film-substrate interface-rigidity”, G. P. Lindberg, T. O'Loughlin, N. Gross, A. Mishchenko, A. Reznik, S. Abbaszadeh, K. S. Karim, G. Belev and B. A. Weinstein, J. of Appl. Phys. 116 (19), 193511(1-6) (2014).
“Optical phonons in spherical core/shell semiconductor nanoparticles: Effect of hydrostatic pressure”, C. Trallero-Giner, F. Comas, G. E. Marques, R. E. Tallman, and B. A. Weinstein, Phys. Rev. B 82, 205426(1-14), (2010).
“Raman Spectroscopy under Pressure in Semiconductor Nanoparticles”, B. A. Weinstein, physica status solidi (b) 244, 368-379 (2007), invited review.
“Raman scattering in β-ZnS”, J. Serrano, A. Cantarero, M. Cardona, N. Garro, R. Lauck, R. E. Tallman, T. M. Ritter, and B. A. Weinstein, Phys. Rev. B 69, 14301-12 (2004).
“Evidence for selective de-localization of N-pair states in dilute GaAs1-xNx”, B.A. Weinstein, S. R. Stambach, T. M. Ritter, J. O. Maclean, and D. J. Wallis, Phys. Rev. B 68, 35336-35345 (2003).
"Effects of Pressure on the Zn-Vacancy in ZnSe: Essential Role of Lattice Relaxation for a Basic C3v Defect", V. Iota and B. A. Weinstein, Phys. Rev. Lett. 81, 4955-4958 (1998).
“Emergence of Deep Levels in n-Type ZnSe Under Hydrostatic Pressure”, T. M. Ritter, B. A. Weinstein, R. M. Park and M. C. Tamargo, Phys. Rev. Lett. 76, 964-967 (1996).
"Forward and Reverse High-Pressure Transitions in Bulk-like AlAs and GaAs Epilayers", U.D. Venkateswaran, L.J. Cui, B. A. Weinstein and F.A. Chambers, Phys. Rev. B45, 9237-9247 (1992).
"Strain Mapping in [111]- and [001]- InGaAs/GaAs Superlattices", U.D. Venkateswaran, L.J. Cui, M. Li, B. A. Weinstein, K. Elcess, C.G. Fonstad and C. Mailhiot, Appl. Phys. Lett. 56, 286 (1990).
"Phase Transitions in AlAs/GaAs Superlattices Under High Pressure", B. A. Weinstein, S. K. Hark, R.D. Burnham and R.M. Martin, Phys. Rev. Lett. 58, 781-785 (1987).
"Pressure-Raman Effects in Covalent and Molecular Solids", B. A. Weinstein and R. Zallen, in: Light Scattering in Solids IV, Topics in Applied Physics, Vol. 54, ed. by M. Cardona, and G. Guntherodt (Springer-Verlag, Berlin, 1984) pp. 463-527. Invited Chapter
"Photoelastic Trends for Amorphous and Crystalline Solids of Differing Network Dimensionality", B. A. Weinstein, R. Zallen, M.L. Slade and A. deLozanne, Phys. Rev. B 24, 4652-4665 (1981).
"Raman Scattering and Phonon Dispersion in Si and GaP at Very High Pressure", B. A. Weinstein and G. J. Piermarini, Phys. Rev. B 12, 1172-1186 (1975).
Patent #5,693,345: "Diamond-Anvil-Cell Assembly", by R. J. Chen and B. A. Weinstein