Selective-area high-quality germanium growth for monolithic integrated optoelectronics

Cataloged from PDF version of article.Selective-area germanium (Ge) layer on silicon (Si) is desired to realize the advanced Ge devices integrated with Si very-large-scale-integration (VLSI) components. We demonstrate the area-dependent high-quality Ge growth on Si substrate through SiO2 windows. The combination of area-dependent growth and multistep deposition/hydrogen annealing cycles has effectively reduced the surface roughness and the threading dislocation density. Low root-mean-square surface roughness of 0.6 nm is confirmed by atomic-force-microscope analysis. Low defect density in the area-dependent grown Ge layer is measured to be as low as 1 × 107 cm−2 by plan-view transmission-electron-miscroscope analysis. In addition, the excellent metal–semiconductor–metal photodiode characteristics are shown on the grown Ge layer to open up a possibility to merge Ge optoelectronics with Si VLSI

Plasmonic backcontact grating for P3HT:PCBM organic solar cells enabling strong optical absorption increased in all polarizations

Cataloged from PDF version of article.In P3HT:PCBM based organic solar cells we propose and demonstrate numerically plasmonic backcontact grating architectures for strong optical absorption enhanced in both transverse-magnetic and transverse-electric polarizations. Even when the active material is partially replaced by the metallic grating (without increasing the active layer film thickness), we show computationally that the light absorption in thin-film P3HT:PCBM is increased by a maximum factor of similar to 21% considering both polarizations under AM1.5G solar radiation and over a half-maximum incidence angle of 45 degrees (where the enhancement drops to its half) compared to the same cell without a grating. This backcontact grating outperforms the typical plasmonic grating placed in PEDOT:PSS layer. (C)2011 Optical Society of America

Volumetric plasmonic resonator architecture for thin-film solar cells

Cataloged from PDF version of article.We propose and demonstrate a design concept of volumetric plasmonic resonators that relies on the idea of incorporating coupled layers of plasmonic structures embedded into a solar cell in enhanced optical absorption for surface-normal and off-axis angle configurations, beyond the enhancement limit of individual plasmonic layers. For a proof-of-concept demonstration in a thin-film organic solar cell that uses absorbing materials of copper phthalocyanine/perylene tetracarboxylic bisbenzimidazole, we couple two silver grating layers such that the field localization is further extended within the volume of active layers. Our computational results show a maximum optical absorption enhancement level of similar to 67% under air mass 1.5 global illumination considering both polarizations. (C) 2011 American Institute of Physics

Superhydrophobic and Omnidirectional Antifreflective Surfaces from Nanostructured Ormosil Colloids

Cataloged from PDF version of article.A large-area superhydrophobic and omnidirectional antireflective nanostructured organically modified silica coating has been designed and prepared. The coating mimics the self-cleaning property of superhydrophobic lotus leaves and omnidirectional broad band antireflectivity of moth compound eyes, simultaneously. Water contact and sliding angles of the coating are around 160 and 10, respectively. Coating improves the transmittance of the glass substrate around 4%, when coated on a single side of a glass, in visible and near-infrared region at normal incidence angles. At oblique incidence angles (up to 60) improvement in transmission reaches to around 8%. In addition, coatings are mechanically stable against impact of water droplets from considerable heights. We believe that our inexpensive and durable multifunctional coatings are suitable for stepping out of the laboratory to practical outdoor applications

Amyloid-like peptide nanofiber templated titania nanostructures as dye sensitized solar cell anodic materials

Cataloged from PDF version of article.One-dimensional titania nanostructures can serve as a support for light absorbing molecules and result in an improvement in the short circuit current (Jsc) and open circuit voltage (Voc) as a nanostructured and high-surface-area material in dye-sensitized solar cells. Here, self-assembled amyloid-like peptide nanofibers were exploited as an organic template for the growth of one-dimensional titania nanostructures. Nanostructured titania layers were utilized as anodic materials in dye sensitized solar cells (DSSCs). The photovoltaic performance of the DSSC devices was assessed and an enhancement in the overall cell performance compared to unstructured titania was observed. © 2013 The Royal Society of Chemistry

Enhanced photoresponse of conformal TiO2/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing angle and atomic layer deposition

Cataloged from PDF version of article.In this study, the authors demonstrate a proof of concept nanostructured photodiode fabrication method via successive glancing angle deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse compared to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO2) was deposited conformally on Ag NRs via ALD. Scanning electron microscopy studies confirmed the successful formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO2 on Ag NRs via ALD. Following the growth of TiO2 on Ag NRs, aluminum metallic top contacts were formed to complete the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a photo response enhancement factor of 1.49 × 102 under a reverse bias of 3 V. © 2014 American Vacuum Societ

Experimental and theoretical investigation of phosphorus in-situ doping of germanium epitaxial layers

Cataloged from PDF version of article.We investigate phosphorus in-situ doping characteristics in germanium (Ge) during epitaxial growth by spreading resistance profiling analysis. In addition, we present an accurate model for the kinetics of the diffusion in the in-situ process, modeling combined growth and diffusion events. The activation energy and pre-exponential factor for phosphorus (P) diffusion are determined to be 1.91 eV and 3.75 x 10(-5) cm(2)/s. These results show that P in-situ doping diffusivity is low enough to form shallow junctions for high performance Ge devices. (C) 2013 Elsevier B.V. All rights reserve

Generation of InN nanocrystals in organic solution through laser ablation of high pressure chemical vapor deposition-grown InN thin film

Cataloged from PDF version of article.We report the synthesis of colloidal InN nanocrystals (InN-NCs) in organic solution through nanosecond pulsed laser ablation of high pressure chemical vapor deposition-grown InN thin film on GaN/sapphire template substrate. The size, the structural, the optical, and the chemical characteristics of InN-NCs demonstrate that the colloidal InN crystalline nanostructures in ethanol are synthesized with spherical shape within 5.9-25.3, 5.45-34.8, 3.24-36 nm particle-size distributions, increasing the pulse energy value. The colloidal InN-NCs solutions present strong absorption edge tailoring from NIR region to UV region. © 2012 Springer Science+Business Media B.V

Volumetric plasmonic resonator architecture for thin-film solar cells

We propose and demonstrate a design concept of volumetric plasmonic resonators that relies on the idea of incorporating coupled layers of plasmonic structures embedded into a solar cell in enhanced optical absorption for surface-normal and off-axis angle configurations, beyond the enhancement limit of individual plasmonic layers. For a proof-of-concept demonstration in a thin-film organic solar cell that uses absorbing materials of copper phthalocyanine/perylene tetracarboxylic bisbenzimidazole, we couple two silver grating layers such that the field localization is further extended within the volume of active layers. Our computational results show a maximum optical absorption enhancement level of ∼67% under air mass 1.5 global illumination considering both polarizations. © 2011 American Institute of Physics

Volumetric plasmonic resonators for very thin organic solar cells

[No abstract available