S. Perkowitz

Raman, infrared, photoluminescence and theoretical studies of the II-VI-VI ternary CdSeTe

We have examined Bridgman-grown zincblende CdSexTe1−x (x < 0.36) by Raman scattering, Fourier transform infrared reflectivity, photoluminescence and theoretical analysis. The Raman data showed evidence of surface structural improvement by long-term room temperature annealing. The combined Raman and infrared data confirmed the interpretation that a third infrared mode besides the CdTe- and CdSe-like transverse optical phonon modes, arose from non-random atomic clustering. Room temperature photoluminescence spectra were obtained and compared with pseudopotential calculations.

Far infrared studies of lattice and free carrier effects in Hg1-xMnxTe ☆

Abstract The far infrared reflectivity of Hg 1- x Mn x Te samples with x = 0.01, 0.06, and 0.11 has been measured between 5.5 and 295 K. For x = 0.06 and T = 5.5 K , fits to a dielectric function including an approximate interband term gave the first determination of m ∗ /m 0 = 0.0059 , and band gap value, -39±10 meV, in good agreement with the result of Bastard et al . The temperature and alloy dependence of the coupled plasmon-phonon modes has also been determined.

AlAs Phonon parameters and heterostructure characterization

Abstract Infrared and Raman spectra from an AlAs-GaAs heterostructure yield phonon parameters for non-oxidized pure AlAs at 300, 77 and 6K, which have not been thoroughly established. Strong infrared interference effects in the heterostructure are identified and produce a large peak near the GaAs LO frequency. This explains an anomalous double peak previously observed in infrared spectroscopy of AlxGa1-xAs-GaAs heterostructures.

Resonance Raman scattering from epitaxial InSb films grown by metalorganic magnetron sputtering

We have examined epitaxial InSb films by Raman scattering for the first time. The films, 0.17–2.67 μm thick, were grown on (100) GaAs substrates by the new technique of metalorganic magnetron sputtering. We observe the first and second order longitudinal optical phonon peaks, the latter enhanced by outgoing resonance with the E1+Δ1 gap of InSb, and an upshift of this gap due to compressive biaxial stress. We also observe an anomalous dependence of stress on film thickness. The Raman data indicate good sample quality despite the large lattice mismatch between InSb and GaAs.

Lattice vibrations of cadmium manganese telluride alloys

Reflectivity spectra in the reststrahlen region (100–250 cm−1) are presented for bulk zinc blende Cd1−xMnxTe crystals at 2, 50, and 300 K and for x=0 to 0.64, covering nearly the entire possible composition range for cubic structure. Kramers‐Kronig analysis gives the transverse and longitudinal phonon frequencies. The Lorentz model confirms these results and also gives mode strengths and damping constants. Compositional dependence of the phonon energies is predicted by the random element isodisplacement model.

Far-infrared reflectance study of coupled longitudinal-optical phonon-hole plasmon modes and transport properties in heavily doped p-type GaAs

We measured room-temperature far-infrared reflectance spectra of ten p-type, Be-doped, molecular-beam-epitaxy-grown GaAs films with hole densities from 6.3×1017 to 2.9×1019 cm-3 and examined the frequency-dependent dielectric function of coupled phonon-heavily damped hole plasmon modes in these samples without the complications that arise in Raman scattering experiments. Both a two-oscillator dielectric function e(ω), and Kukharskiis factorized form eK(ω) for the dielectric function, reproduce the data well. The plasmon-like modes clearly appear in the reflectance spectra, although they are suppressed in the Raman spectra, and we find that their frequencies are best given by finding the solutions of e(ω)=0 in the complex ω-plane. The infrared data also accurately yield the hole drift mobilities when we consider values for the Hall scattering factor in p-type GaAs.

Raman scattering characterization of high‐quality Cd1−xMnxTe films grown by metalorganic chemical vapor deposition

Cd1−xMnxTe films (thickness ∼0.5 μm, x=0.10–0.37) have been grown by metalorganic chemical vapor deposition on commercial GaAs and glass substrates with and without buffer layers of CdTe and CdS. Raman scattering shows the films to be of high quality, despite the large film‐substrate lattice mismatch. CdTe‐like and MnTe‐like phonon lines are sharp and strong in first and second order with widths ≤10 cm−1, and clearly appear in combinations up to fourth order. Raman and photoluminescence analysis also establish an optimum growth temperature and limits on the fraction of Mn.

Infrared properties of single crystal MgO, a substrate for high temperature superconducting films

We report and analyze the infrared properties of single crystal MgO, an important substrate for high T(c), superconducting films, from 10 to 280 cm(-1) and 20-300 K.

Multiple phonon overtones in ZnTe

Abstract We have examined resonance Raman scattering from bulk Bridgman-grown ZnTe, under excitation at eight photon energies covering 2.409 – 2.707 eV. Up to the 8th harmonic of the longitudinal optical (LO) phonon peak appeared, due to the outgoing resonance of LO phonons with the fundamental band gap. We compare the observed dependence of the intensity of the harmonics on order number m to a simple formula derived from the basic theory of Raman scattering, which includes a resonant term and a decreasing m −4 term. Polarization data support resonance Raman scattering as the origin of the multiphonon lines.

Temperature dependence of the far-infrared ordinary-ray optical constants of sapphire

The refractive index n(ν) and absorption coefficient α(ν) of c-cut sapphire are measured at the temperatures 5.5, 30, 60,150, 200, 250, and 300 K for frequencies between 30 and 230 cm−1. Values given for n are accurate to within 1% and those for α to within 5%. Polynomial fits are included, and evidence of multiphonon absorption is also shown.