Instability phenomena in microcrystalline silicon films

Microcrystalline silicon (μc-Si:H) for solar cell applications is investigated with respect to the material stability upon treatment of the material in various environments, followed by annealing. The material can be separated into two groups: (i) material with high crystalline volume fractions and pronounced porosity which is susceptible to in-diffusion of atmospheric gases, which, through adsorption or oxidation affect the electronic properties and (ii) compact material with high or low crystalline volume fractions which show considerably less or no influence of treatment in atmospheric gases. We report the investigation of such effects on the stability of μc-Si:H films prepared by plasma enhanced chemical vapour deposition and hot wire chemical vapour deposition

Особенности разработки и функционала универсальной парковочной станции для персонального электротранспорта

N-type microcrystalline silicon carbide layers prepared by hot-wire chemical vapor deposition were used as window layers for microcrystalline silicon n-i-p solar cells. The microcrystalline silicon intrinsic and p-layers of the solar cells were prepared with plasma-enhanced chemical vapor deposition at a very high frequency. Amorphous silicon incubation layers were observed at the initial stages of the growth of the microcrystalline silicon intrinsic layer under conditions close to the transition from microcrystalline to amorphous silicon growth. 'Seed layers' were developed to improve the nucleation and growth of microcrystalline silicon on the microcrystalline silicon carbide layers. Raman scattering measurement demonstrates that an incorporation of a 'seed layer' can drastically increase the crystalline volume fraction of the total absorber layer. Accordingly, the solar cell performance is improved. The correlation between the cell performance and the structural property of the absorber layer is discussed. By optimizing the deposition process, a high short-circuit current density of 26.7 mA/cm(2) was achieved with an absorber layer thickness of 1 pm, which led to a cell efficiency of 9.2%. (C) 2007 Elsevier B.V. All rights reserved

Combining conductive atomic force microscopy with electrically detected magnetic resonance

We present the design and implementation of a scanning probe microscope, which combines electrically detected magnetic resonance (EDMR) and (photo-)conductive atomic force microscopy ((p)cAFM). The integration of a 3-loop 2-gap X-band microwave resonator into an AFM allows the use of conductive AFM tips as a movable contact for EDMR experiments. The optical readout of the AFM cantilever is based on an infrared laser to avoid disturbances of current measurements by absorption of straylight of the detection laser. Using amorphous silicon thin film samples with varying defect densities, the capability to detect a spatial EDMR contrast is demonstrated. Resonant current changes as low as 20 fA can be detected, allowing the method to realize a spin sensitivity of 8×106spins/√Hz at room temperature

Thin Film Silicon: Research and Application for Solar Energy Conversion

Recent research and application activities with thin film silicon for solar energy conversion include transparent flexible substrates witha nano-imprint process for enhanced light-trapping, silicon-carbon and silicon-oxygen alloys for thin film and heterojunction solar cells, stacked solar cells as generators for integrated photocatalytic water splitting devices, concepts for integrated battery charge systems, and processing of thin film silicon from liquid precursors. Results from some of these new activities will be highlighted and state-of-the art device applications will be presented