Electronic properties of very thin native SiO2/a-Si:H interfaces and their comparison with those prepared by both dielectric barrier discharge oxidation at atmospheric pressure and by chemical oxidation

The contribution deals with electronic properties of thin oxide/amorphous hydrogenated silicon (a-Si:H) measured by capacitance-voltage (C-V) and charge version of deep level transient spectroscopy (Q-DLTS). The interest was focused on the studies of the interface properties of very thin dielectrics formed by dielectric barrier discharge (DBD) or natively on the a-Si:H layer. These properties were compared with those of oxide layers prepared by chemical oxidation in HNO3. The DBD was used for the preparation of a very thin SiO2 layer on a-Si:H for the first time to our knowledge. Preliminary electrical measurements confirmed that a very low interface states density was detected in the case of the native oxide/a-Si:H and DBD oxide/a-Si:H

Reactivity of Au with ultrathin Si layers: A photoemission study

We present a photoemission study on reactivity of the Au-Si system. We studied gold films evaporated atop ultrathin silicon layers previously deposited on GaAs. Following analysis of both the Si 2p core level and the Au 5d valence band spectra related response, we show that the reaction mechanism between Au and Si is affected by structural imperfections of the silicon layer. This is in sharp opposition to some current models of the reactivity mechanism. (C) 2001 American Institute of Physics

Experimental study of passivating ion-beam-induced distributed energy levels in n-GaAs by hydrogen species from boiling water

Moderately doped n-GaAs substrates were etched by a 250 eV Ar+-ion beam and subsequently immersed up to 80 min in boiling distilled water, to remove the radiation damage. Comparative studies of the remaining damage to the GaAs surface region, benefiting from both alternating current (capacitance DLTS, high-frequency C-V) and time-domain (charge DLTS, feedback-charge C-V) techniques, were conducted. Prior to the passivation in water, there was a spectrum of deep levels distributed in energy, responsible for a large capacitance dispersion in Al GaAs Schottky junctions at ambient temperatures. Apart from significant differences between the responses to pulsed excitation in the frequency and time domains, the damage due to the ion beam is effectively reduced by hydrogenation. In contrast to the case of a discrete energy level, efficiency of passivating distributed levels is difficult to assess as a scalar quantity. Long-term stability of the deep-level neutralization over a period of 16 months has been confirmed. © 1995

Very thin and ultrathin oxide/a-Si:H structures and polycrystalline-Si MOS type of solar cells

This presentation looks at very thin and ultrathin oxide/a-Si:H structures and polycrystalline-Si MOS type of solar cell

Multifractal analysis of textured silicon surfaces

Pyramidal textures with random distribution of texture shapes on crystalline Si wafers substantially reduce reflection losses of substrates for high efficiency solar cells, detectors and similar applications. In this work random pyramids on n type Si wafers were prepared by anisotropic surface etching in potassium hydroxide KOH solution. The morphology of pyramidal shapes was examined by the AFM method and reveals high complexity of the surface structure. Properties of AFM observed pyramidal textures were characterized by the statistical and multifractal methods. This approach provides good platform for the distinguishing between fine details in the pyramidal distributions. Significant correlation between the fractal properties of surface texture and its optical properties characterized by the spectral reflectance function is observe

X-ray photoemission and photoreflectance study of Au ultrathin Si/n-GaAs Schottky contacts and hydrogen plasma treated semi-insulating GaAs surfaces

The paper presents room temperature photoreflectance measurements carried out on the Au/ultrathin Si/n-crystalline GaAs structure with the silicon interlayer thickness gradually changing from about 4-27 Angstrom prepared in situ under ultra-high-vacuum conditions. A continuous change of the phase shift of the corresponding photoreflectance signal of more than 180 degrees has been observed in the Eg-critical-point oscillation of GaAs depending on the Si interlayer thickness. The explanation of the effect is based on the composition changes of the Au/Si interface monitored by X-ray photoelectron spectroscopy. The photoreflectance results are compared to the photoreflectance signal phase changes observed on the semi-insulating GaAs surfaces exposed to the low-temperature hydrogen plasma. (C) 1999 Elsevier Science S.A. All rights reserved

Low-energy argon ion beam treatment of a-Si:H/Si structure

The results of several surface-sensitive techniques applied to the investigation of ion beam-treated a-Si:H/crystalline silicon structures, such as deep-level transient spectroscopy (DLTS), photoluminescence at 6 K and room temperature, and X-ray diffraction at grazing incidence (XRDGI) are presented. Three important results follow from this contribution. (i) Two groups of gap states with thermal activation energies of 0.71 and 0.84 eV were identified and found to be sensitive to illumination, this property exhibiting metastable character; we suppose effects similar to those observed in the porous silicon/silicon and a-Si:H/silicon structures. (ii) Broader luminescence peaks were identified optically with the energies lying in the range of 0.7 to 0.95 eV, the most distinct one being at 0.85 eV. (iii) X-ray reflection at 2θ∼28° has been found as the reflection suitable for tracing the structural properties of a-Si:H layer

Photoluminescence properties of a-Si:H based thin films and corresponding solar cells

This chapter looks at photoluminescence properties of a-Si:H based thin films and corresponding solar cell

On a transformation of a-Si:H surface due to very low-energy particle impacts to very thin insulating overlayer of device quality

A chapter on a transformation of a-Si:H surface due to very low-energy particle impacts to very thin insulating overlayer of device qualit

Investigation of electrical, structural, and optical properties of very thin oxide/a-Si:H/c-Si interfaces passivated by cyanide treatment

This chapter looks at the investigation of electrical, structural, and optical properties of very thin oxide/a-Si:H/c-Si interfaces passivated by cyanide treatmen