Bending properties in oxidized porous silicon waveguides

The greatest limit in high-speed communications between different circuit blocks is due to the delays introduced by metal interconnections. Knock-down wire communication bottleneck is, therefore, one of the best goals that current research could reach in the held of fast electronics. A possible solution is to build fast optical links and even better if the technology is based on silicon. To attain these ends, we have made studies into possibility to fabricate optical waveguide based on oxidized porous silicon. In the last few years, such a device: was realized and characterized. Waveguiding in the visible and in the near infrared was demonstrated, With propagation losses of about 3-5 dB/cm for a light with a wavelength of 632.8 nm. Moreover, a design feature of an integrated waveguide based on oxidized porous silicon is that it offers a spontaneous bending of the waveguiding layer at its ends. The edge bending is provided by a convex camber of a leading edge of forming porous silicon. This bending can be exploited to promote a vertical light output with no use of any additional devices. The paper discusses the properties of edge bending, evaluation of the light losses depending on the radius of curvature, and analysis of possibilities to reduce these losses. (C) 2001 Elsevier Science Ltd. All rights reserved

Er-doped Oxidized Porous Silicon Waveguides

The present work reports Er-doped channel oxidized porous silicon waveguides (OPSWG) formed from n+-type Si by the two-step anodisation process. Er has been introduced into porous silicon before oxidation by a cathodic treatment in 0.1 M Er (NO3)3 aqueous solution. A correlation between Er concentration and refractive index profiles has shown dominant core doping with Er relative to cladding regions. Reported Er concentration of 0.8 at.% in the OPSWG is large enough to attain the amplification effect

Technological aspects of oxidated porous silicon waveguides

Technological aspects related to the fabrication of buried oxidized porous silicon waveguides (OPSWG) as the influence of swirl defects and a suitable epitaxial method to bury OPSWG have been investigated. The influence of swirl defects on OPSWG performances is presented. The formation of a non-homogeneous porous silicon, caused by swirl defects, results in an incomplete oxidation and in an increase of optical loses. The idea of burying waveguides has been tested by a suitable epi process covering using dichlorosilane and silane as reacting gases. The paper presents and discusses the preliminary results. In this paper, are presented the technological studies related to the fabrication of buried OPSWG: (i) swirl defects influence on the structure and on the guiding properties of OPSWG; (ii) epitaxial deposition process suitable for the realization of defects free silicon layer over the OPSWG. (C) 2002 Elsevier Science B.V. All rights reserved

Buffer layer influence on guiding properties of oxidized porous silicon waveguides

We studied the influence of the thickness and porosity of the buffer layer on the guiding properties of oxidized porous silicon waveguides (OPSWG). It is demonstrated how a modified anodization process acts on the porosity of the final oxidized porous silicon. In this way, it is possible to control the refractive index jump between the core of OPSWG made of compact silicon dioxide and the bottom buffer layer made of porous silicon dioxide. The adoption of a double-step anodization process decreases the propagation losses to 0.5 dB/cm against the 8 dB/cm measured for the waveguide realized using a single-step anodization. The main reason seems not to be the increase of the difference of refractive index values but the more homogeneous buffer layer obtained along the core of the waveguide. This homogeneous layer permits a better lateral confinement of the light as demonstrated by spatial refractive index profile measurement. (C) 2002 Elsevier Science B.V. All rights reserved

Characterization of integrated optical waveguides based on oxidized porous silicon

Integrated optical waveguides based on oxidized porous silicon were fabricated by means of traditional silicon technology. Near-field pattern and out-of-plane scattering losses were measured to characterize optical properties of the waveguides. Strong confinement of light within the core of the waveguides as well as optical losses of about 5 dB/cm have been demonstrated in the visible range. The achieved results make the waveguides promising in optoelectronics use

Oxidized porous silicon: From dielectric isolation to integrated optical waveguides

A brief review of 20-years research of formation, processing and utilizing of oxidized porous silicon (OPS) is presented. Electrolytes to form porous silicon (PS) layers, special features of PS chemical cleaning and thermal oxidation are discussed. OPS application for dielectric isolation of components of bipolar ICs and for the formation of silicon-on-insulator structures has been demonstrated. Although these OPS-based techniques have found limited current commercial use, experience gained is applicable to the fabrication of optoelectronic devices. Specifically, integrated optical waveguides based on OPS have been developed

Porous silicon: a buffer layer for PbS heteroepitaxy

In the present work, we report on the heteroepitaxial growth of PbS on porous silicon (PS). Epitaxial PbS films were grown by MBE on the surface of PS formed on the n+-type silicon (111) substrate. The films were comparable with films grown on BaF2 substrates. Beneficial influence of a PS buffer layer on the structure and properties of PbS epitaxial films was supported by implementation of sensitive Schottky-barrier photodiodes fabricated in these films

Porus Silicon: a Buffer Layer for PbS Heteroepitaxy

In the present work, we report on the heteroepitaxial growth of PbS on porous silicon (PS). Epitaxial PbS films were grown by MBE on the surface of PS formed on the n(+)-type silicon (111) substrate. The Films were comparable with films grown on BaF2 substrates. Beneficial influence of a PS buffer layer on the structure and properties of PbS epitaxial films was supported by implementation of sensitive Schottky-harrier photodiodes fabricated in these films

Oxidized porous silicon: from dielectric isolation to integrated optical waveguides

A brief review of 20-years research of formation, processing and utilizing of oxidized porous silicon (OPS) is presented. Electrolytes to form porous silicon (PS) layers, special features of PS chemical cleaning and thermal oxidation are discussed. OPS application for dielectric isolation of components of bipolar ICs and for the formation of silicon-on-insulator structures has been demonstrated. Although these OPS-based techniques have found limited current commercial use, experience gained is applicable to the fabrication of optoelectronic devices. Specifically, integrated optical waveguides based on OPS have been developed