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Your search keyword '"Pollak, F.H."' showing total 107 results
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107 results on '"Pollak, F.H."'

1. Moss-Burstein and plasma reflection characteristics of heavily doped n-type In(sub x)Ga(sub 1-x)As and InP(sub y)As(sub 1-y)

Author

Charache, G.W., DePoy, D.M., Raynolds, J.E., Baldasaro, P.F., Miyano, K.E., Holden, T., Pollak, F.H., Sharps, P.R., Timmons, M.L., Geller, C.B., Mannstadt, W., Asahi, R., Freeman, A.J., and Wolf, W.

Subjects
Photovoltaic power generation -- Research, Electrooptical devices -- Research, Optoelectronic devices -- Research, Filters (Separation) -- Research, Physics
Abstract

A study on suitable plasma spectral control filters for thermophotovoltaic generation systems investigated the optical properties of heavily doped low-band-gap III-V Results indicate that the low effective masses of degenerately doped n-In(sub x)Ga(sub 1-x)As and n-InP(sub y)As(sub 1-y) make these materials ideal plasma filters for thermophotovoltaic applications. This ensures high majority carrier mobility and a large Moss-Burstein shift at carrier concentrations exceeding 5 x 10 to the 19th power/cm3.

Published
1999

4. Optical and electrical characterization of an AlGaAs/GaAs heterostructure

Author

Gray, M.L. and Pollak, F.H.

Subjects
Hall effect -- Measurement, Epitaxy -- Research, Quantum wells -- Research, Physics
Abstract

AlGaAs/GaAs heterostructure, grown by using molecular beam epitaxy, is analyzed by photoreflectance (PR) spectroscopy and by measuring the Hall effect. The quality of the undoped GaAs, the aluminium composition of Al\GaAs layers, impurity diffusion and the quantum well widths are determined by using quantum and photoreflectance spectrum. The electrical properties of the heterostructure is yielded by the identification of the photoreflectance features.

Published
1993

8. Excitonic transitions in β-FeSi[sub 2] epitaxial films and single crystals.

Author

Birdwell, A.G., Shaffner, T.J., Chandler-Horowitz, D., Buh, G.H., Rebien, M., Henrion, W., Stauß, P., Behr, G., Malikova, L., Pollak, F.H., Littler, C.L., Glosser, R., and Collins, S.

Subjects
REFLECTANCE, EPITAXY, THIN films, CRYSTALS, MATERIALS at low temperatures, EXCITON theory
Abstract

Photoreflectance spectra were obtained from an epitaxial film and a bulk single crystal of β-FeSi[sub 2] at low temperatures (T<=180 K). A model based on the results of low-temperature absorption [M. Rebien et al., Appl. Phys. Lett. 74, 970 (1999)] was used to describe the main features of the spectra. In agreement with the absorption results, transitions corresponding to the ground state and first excited state of the free exciton were observed in both the epitaxial film and single crystal. However, additional subband gap features are revealed in the photoreflectance spectra of the thin film. It is suggested that these may be related to impurity transitions or an impurity transition plus a bound exciton resonance. From the analysis of the spectra taken on the thin film, over a temperature range of 12–180 K, we extract a free exciton binding energy of (0.009±0.002) eV and a direct energy gap at T=0 K of (0.934±0.002) eV. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2004
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12. Excitonic transitions in beta-FeSi2 epitaxial films and single crystals

Author

Birdwell, A.G., Shaffner, T.J., Horowitz, D. Chandler-, Buh, G.H., Rebien, M., StauB, P., Behr, G., Malikova, L, Pollak, F.H, Littler, C.L., Glosser, R, and Collins, S.

Subjects
Transition metal compounds -- Research, Exciton theory -- Research, Reflectance spectroscopy -- Research, Silicon -- Optical properties, Iron -- Optical properties, Physics
Abstract

Photo reflectance spectra were obtained from an epitaxial film and a bulk single crystal of beta-FeSi2 at low temperature, a model based on the results of low-temperature absorption was used to describe the main features of the spectra. Transitions corresponding to the ground state and first exited state of the free excitation, in agreement with the absorption results, were observed in both epitaxial film and single crystal.

Published
2004

30. Photoreflectance study of surface photovoltage effects at (100)GaAs surfaces/interfaces.

Author

Yin, X., Chen, H-M., Pollak, F.H., Chan, Y., Montano, P.A., Kirchner, P.D., Pettit, G.D., and Woodall, J.M.

Subjects
REFLECTANCE, PHOTOVOLTAIC cells, GALLIUM arsenide
Abstract

Details a photoreflectance study of surface photovoltage effects on the determination of Fermi level pinning on n-gallium arsenide (GaAs) in air and with W-metal coverage as a function of temperature and light intensity. Photoreflectance spectrum at room temperature; Measured barrier height.

Published
1991
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44. Photoreflectance of GaAs doping superlattices

Author

Shen, X.C., primary, Shen, H., additional, Parayanthal, P., additional, Pollak, F.H., additional, Schulman, J.N., additional, Smirl, Arthur L., additional, McFarlane, R.A., additional, and D'Haenens, Irnee, additional

Published
1986
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