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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]

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.

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.

We report the growth and characterization of patterned ZnCdSe/ZnCdMgSe quantum-well (QW) structures grown adjacent to each other on a single InP substrate. Each structure emits at a different wavelength range spanning the visible range. Stripe and square-shaped QW structures of different emission wavelengths, with lateral dimensions between 15 and 60 μm, were deposited sequentially by shadow mask selective area epitaxy (SAE) steps. Conventional and microphotoluminescence measurements were used to characterize the patterned QWs. They exhibit well-defined excitonic emission in the red, yellow, and green regions of the visible spectrum. This result demonstrates the feasibility of fabricating integrated full-color light emitting diode and laser-based display elements and white light sources using the ZnCdMgSe material system and shadow mask SAE. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]