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Up to now, all high frequency switching experiments on ferromagnetic semiconductors have involved light induced switching, which is not compatible with integrated circuits. We employed all-electrical techniques to study the response of (Ga,Mn)As to a magnetic field pulse. A field pulse was applied through a coplanar waveguide and the magnetization was read out by anisotropic magnetoresistance. We demonstrated that full magnetization switching by domain wall nucleation and propagation can be triggered by pulses as short as 800 ps, combining the effect of the pulsed field and a heat-induced reduction of the coercive field. [ABSTRACT FROM AUTHOR]

Presents the preparation of polycrystalline silicon solar cells using a conventional diffusion and screen printed metallization method. Application of a dicing saw and beveled blades for the V-groove formation; Comparison with the standard nongrooved structure.

Examines the passivation of solar cells fabricated using casted multicrystalline silicon from Eurosolare. Description of the optimum passivation scheme; Increase of the efficacy of the solar cells with the combination of phosphorus gettering and read aluminum treatments.

Investigates the molecular beam epitaxial growth of InAsSb on gallium arsenide (GaAs)-coated patterned silicon (Si) substrates. Comparison of the InAsSb epilayer morphology for different substrate conditions; Threaded defect density of the InAsSb layers; Evidence of a regular array of misfit dislocations.

The influence of trace metal impurities of low-temperature undoped amorphous silicon by homogeneous chemical vapor deposited a-Si:H has been explored for the first time. The metal impurities Ni, Cr, and Fe cause a shift of the transition temperature for the double-activated regime to a relatively low value. However, Ga and B impurities quench the photoluminescence intensity at a low temperature. Both of them cause weak photoemission of the films at room temperature. The shift of the transition temperature can be explained by the presence of non-radiative deep recombination centers. The quenching of the photoluminescence intensity is caused by the presence of nonradiative recombination centers. [ABSTRACT FROM AUTHOR]

Novel methods of GaAs surface passivation are investigated. Passivation is acheived by simple chemical treatments using aqueous solutions of Na2S, KOH, RuCl3, and K2Se. GaAs pn homojunction solar cells are used to evaluate the effectiveness of these passivation techniques. A significant reduction in minority-carrier surface recombination velocity is demonstrated. In the best case, the surface recombination velocity decreased from 5×106 cm/s (untreated surface) to 103 cm/s. In addition, we observe improvements in solar cell photogenerated current, short wavelength spectral response, open-circuit voltage, and junction ‘‘dark’’ current. [ABSTRACT FROM AUTHOR]

A gallium arsenide film is grown embedded in masked pre-etched wells in silicon vicinal (001) substrates by molecular beam epitaxy. The morphology and crystallinity of the embedded GaAs on Si layers are identical to those of large area GaAs on Si grown on the same wafer, as indicated by the comparison of Nomarski contrast photomicrographs and electron channeling patterns. High-resolution electron microscope images reveal the epitaxial relation of the GaAs/Si interface on the bottom and the sidewall of the wells. On the slope most of the dislocations are restricted to a narrow region near the interface. The same photoluminescent behavior is found for the GaAs deposit in the different silicon environments. This embedded growth technique is suitable for realization of a coplanar GaAs on Si surface. [ABSTRACT FROM AUTHOR]

Epitaxial growth of phosphorus-doped silicon deposited at 250 °C from a radio-frequency glow discharge from SiH4 is demonstrated by high-resolution electron microscopy (HREM) and spreading resistance profile measurements. Thin epitaxial films are present at the interface between (100) Si substrates and hydrogenated amorphous silicon. After recrystallization at 700 °C, single-crystal layers are obtained, in which HREM reveals extensive twinning. The fact that epitaxial growth can take place at 250 °C in a system with a background pressure of only 5×10-6 mbar can be attributed to the presence of species in the SiH4 plasma that reduce the native oxide and the use of HF in the cleaning procedure. [ABSTRACT FROM AUTHOR]

Describes a fabrication process for blue response improvement in low-cost polycrystalline silicon solar cells. Creation of a selective emitter; Comparison of the parameters of solar cells with different types of emitters; Advantages of the proposed process.