Jamila Boudaden - Academia.edu (original) (raw)

Papers by Jamila Boudaden

Research paper thumbnail of Deposition of micro crystalline silicon films using microwave plasma enhanced chemical vapor deposition

Research paper thumbnail of Review—Energy Autonomous Wearable Sensors for Smart Healthcare: A Review

Journal of The Electrochemical Society

Energy Autonomous Wearable Sensors (EAWS) have attracted a large interest due to their potential ... more Energy Autonomous Wearable Sensors (EAWS) have attracted a large interest due to their potential to provide reliable measurements and continuous bioelectric signals, which help to reduce health risk factors early on, ongoing assessment for disease prevention, and maintaining optimum, lifelong health quality. This review paper presents recent developments and state-of-the-art research related to three critical elements that enable an EAWS. The first element is wearable sensors, which monitor human body physiological signals and activities. Emphasis is given on explaining different types of transduction mechanisms presented, and emerging materials and fabrication techniques. The second element is the flexible and wearable energy storage device to drive low-power electronics and the software needed for automatic detection of unstable physiological parameters. The third is the flexible and stretchable energy harvesting module to recharge batteries for continuous operation of wearable sensors. We conclude by discussing some of the technical challenges in realizing energy-autonomous wearable sensing technologies and possible solutions for overcoming them.

Research paper thumbnail of Towards Low Cost and Low Temperature Capacitive CO2 Sensors Based on Amine Functionalized Silica Nanoparticles

Nanomaterials

Hybrid materials based on inorganic particles and an organic polymer were developed and used as a... more Hybrid materials based on inorganic particles and an organic polymer were developed and used as an efficient sensing material for carbon dioxide (CO2). The sensing material consists of fumed silica that is functionalized with an organic polymer, polyethylenimine, by means of the impregnation method. The organic polymer is effectively immobilized around the silica nanoparticles and confirmed by infrared spectroscopy. Thermogravimetric analysis proves the thermal stability of the sensing material. CO2 capacitive sensors operating at temperatures lower than 70 °C were fabricated by depositing a thin layer of hybrid sensing material on interdigitated gold electrodes. Impedance spectroscopy explored the sensing capability of the hybrid organic–inorganic material towards CO2 in the presence of different relative humidity levels, as well as its stability and reversibility. This strategy to couple organic and inorganic materials as a sensing layer for CO2 paves the way for the design of a l...

Research paper thumbnail of An Approach to Reduce Greenhouse Gases in the Semiconductor Industry Using F2 Dissociated in Plasma for CVD Chamber Cleaning

Applied Sciences

The gases used in industrial cleaning processes are considered greenhouse gases with a high globa... more The gases used in industrial cleaning processes are considered greenhouse gases with a high global warming potential (GWP). It is important to provide a viable alternative chemical vapor deposition (CVD) cleaning gas that is capable of removing efficiently deposited layers on the CVD chamber inner wall and other parts of the apparatus. The cleaning gas has to be environmental friendly in order to avoid accentuation of the global warming phenomena. Besides that, the alternative cleaning gas should be compatible with the existing gas delivery system and the CVD equipment that is already used by industrial companies. Only by fulfilling the three requirements mentioned above is it possible to replace the well-established cleaning gases. In this project, an F 2-gas mixture for the in-situ cleaning of CVD chambers has been studied and compared with conventional cleaning methods. The conventional cleaning process is defined as a cleaning procedure using either C 2 F 6 in RF plasma discharge or NF 3 in remote plasma discharge.

Research paper thumbnail of Enzymatic Sensor Based on Dye Sensitized TiO2 Electrode for Detection of Catechol in Water

Research paper thumbnail of Method to Study Water Diffusion into Polymers

Proceedings

We designed and realized a low cost relative humidity (RH) capacitive sensor having an interdigit... more We designed and realized a low cost relative humidity (RH) capacitive sensor having an interdigitated transducer coated with a cheap sensing material working at room temperature (polyimide). Thermally perturbed diffusion of water molecules into the polyimide layer is studied by heating the sensor locally and measuring the sensor capacitance change. The swelling and deswelling model is applied to determine the time constant of involved processes. This simple method, using an evaluation kit developed by our group, to measure the sensor capacitance and to study the diffusion process of water molecules into polyimide could be generalized to analyze the gas diffusion processes into polymer based sensing layer generally used in the field of gas chemical sensors.

Research paper thumbnail of Capacitive CO2 Sensor

Proceedings

The objective of the present paper is to provide a concept for a chemical sensor having a small s... more The objective of the present paper is to provide a concept for a chemical sensor having a small size, a low power consumption and a high reliability for sensing CO2 under different humidity levels at atmospheric pressure, while maintaining a long term stability under working conditions. A high temperature regeneration process of the sensing layer is unneeded to ensure a long term stability of the sensing material. This objective is achieved by using a hybrid organic-inorganic nanomaterial, consisting of inorganic nanoparticles functionalized with an amine-based polymer.

Research paper thumbnail of Multilayer films for coloured glazed solar collectors

Research paper thumbnail of Simultaneous bulk hydrogen passivation and selective emitter formation assisted by ECR-plasma applied to industrial mc-Si solar cells

Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036), 2000

ABSTRACT The authors present a new way of realising a selective emitter, using the simultaneous e... more ABSTRACT The authors present a new way of realising a selective emitter, using the simultaneous etching and hydrogenation properties of the ECR-H 2 plasma (electron cyclotron resonance hydrogen plasma). The impact of the H2-plasma on multicrystalline silicon (POLIX TM) is studied in terms of bulk lifetime. It is shown that during the hydrogenation step, the ECR-plasma etches back the emitter surface at a rate of about 100 nm/hour. Besides, on sheet resistance mappings, they have observed that the etch rate depends on grain orientation. The etch-back is used to form the selective emitter during the hydrogenation process. Solar cells were realised using the screen-printed contacts as a mask against the plasma effect. The short circuit current can gain more than 1 mA/cm2, the gain coming from the whole spectral range, this due to the less recombinating surface and the hydrogenated bulk material

Research paper thumbnail of Coatings for colored glazed thermal solar collectors and solar active glass facades

Research paper thumbnail of Towards colored glazed thermal solar collectors

Research paper thumbnail of Designing thin film multilayers for colored glazed thermal collectors

Research paper thumbnail of Photoemission study of the iron-induced chemical reduction of silicon native oxide

Surface Science, 2003

Samples consisting of Fe deposited onto a Si wafer covered with its native oxide layer have been ... more Samples consisting of Fe deposited onto a Si wafer covered with its native oxide layer have been studied by photoelectron spectroscopy for different Fe coverages and different deposition techniques involving different kinetic energies for the deposited Fe atoms. We find that the Fe atoms are buried into the substrate even for low kinetic energy techniques, and that a reduction of the Si oxide concomitant with an oxidation of the Fe occurs. This reaction can be assisted by increasing the kinetic energy of the Fe atoms.

Research paper thumbnail of Thin film multilayer design types for colored glazed thermal solar collectors

Solar Energy Materials and Solar Cells, 2005

Multilayered interference filters of dielectric thin films have been designed for the application... more Multilayered interference filters of dielectric thin films have been designed for the application as energy-efficient coloration of collector cover glasses. The optical behavior of the designed multilayers is analyzed by computer simulations yielding the CIE color coordinates, the relative luminosity, the degree of solar transmission, and a figure of merit which is a measure for the energy effectiveness of the coloration. A high performance should be achieved with a number of individual layers reasonable for large-scale deposition. Constraints on the refractive index of the dielectric films are given by the availability of suitable thin film materials. The challenge lies in finding the best combination of material choice and layer thicknesses. We describe several types of multilayer designs for which the computer simulations yield promising results.

Research paper thumbnail of Multilayered Al2O3/SiO2 and TiO2/SiO2 coatings for glazed colored solar thermal collectors

Solar Energy Materials and Solar Cells, 2005

Our aim is to study the possibility of integrating dielectric multilayer films deposited on glass... more Our aim is to study the possibility of integrating dielectric multilayer films deposited on glass substrates as a colored glazed cover for thermal solar collectors and building faces. The cover glass should ideally reflect only a narrow band of visible light while transmitting the rest of the sunlight spectrum to minimize energy loss. A compromise between the visible reflectance and the solar transmission has to be found. In our multilayer interference filters, we used two materials having, respectively, a high and a low refractive index. We studied two cases: Al 2 O 3 / SiO 2 and TiO 2 /SiO 2. The thin films were deposited by reactive magnetron sputtering. In situ XPS characterizations were carried out for each film by transferring the sample from the deposition chamber to an ultra-high vacuum analysis chamber without breaking the vacuum. The growth rate of TiO 2 , SiO 2 and Al 2 O 3 single layers on Si substrates were monitored by in situ laser reflectometry. Spectroscopic ellipsometry was used to determine the optical constants and the thicknesses of every individual dielectric layer. Reflectivity measurements of the experimentally realized dielectric multilayers deposited on glass substrates confirmed their transparency and their good accordance with the simulation. The multilayers were also characterized by their solar transmission, visible reflectance and a factor of merit.

Research paper thumbnail of Towards coloured glazed thermal solar collectors

Solar Energy Materials and Solar Cells, 2004

ABSTRACT Multilayers of TiO2 and SiO2 dielectric coatings deposited by reactive sputtering have b... more ABSTRACT Multilayers of TiO2 and SiO2 dielectric coatings deposited by reactive sputtering have been characterized by X-ray photoelectron spectroscopy, in situ real-time laser reflectometry, spectroscopic ellipsometry and spectrophotometry. Measurements have been performed on individual dielectric layers of TiO2, SiO2 and multilayers. The experiments show a good agreement between the different techniques. Optical properties can be modelled properly using a Cauchy dispersion model. The optical constants of an individual layer are confirmed by the optical measurements on more complex multilayer structures. Reflectivity of the three-layer films fulfils the requirements for a first step towards coloured glazed thermal solar collectors.

Research paper thumbnail of Electrical properties of multicrystalline silicon produced by electromagnetic casting process: Degradation and improvement

Solar Energy Materials and Solar Cells, 2001

The electrical properties of boron-doped multicrystalline silicon for photovoltaic applications, ... more The electrical properties of boron-doped multicrystalline silicon for photovoltaic applications, elaborated by the cold crucible pulling process, are studied by the photoconductivity decay method and the electron beam-induced current measurement technique. The bulk lifetime mapping of the minority carriers in the as-grown silicon wafers is drawn up using both the techniques. Moreover, the consequence of phosphorus doping on the recombination

Research paper thumbnail of Comparison of phosphorus gettering for different multicrystalline silicon

Solar Energy Materials and Solar Cells, 2002

The influence of a rapid thermal treatment on multicrystalline silicon produced by ElectroMagneti... more The influence of a rapid thermal treatment on multicrystalline silicon produced by ElectroMagnetic Casting process (Emix® and Sitix®) and by directional solidification (Polix®), are investigated and compared in this paper. We have studied bifacial diffusion of phosphorus in this multicrystalline silicon and its gettering effect on the minority carrier lifetime measured by the photoconductivity decay technique. The diffusion is carried

Research paper thumbnail of Phosphorous emitter etch back and bulk hydrogenation by means of an ECR-hydrogen plasma applied to form a selective emitter structure on mc-Si

Solar Energy Materials and Solar Cells, 2002

In this paper, we study the effect of hydrogen-electron cyclotron resonance plasma (ECR plasma) o... more In this paper, we study the effect of hydrogen-electron cyclotron resonance plasma (ECR plasma) on the phosphorous-doped emitter of a solar cell based on multicrystalline silicon (POLIX s). The purpose of this experiment is to realise a selective emitter structure, using the front metal contacts as a mask. We show that hydrogen plasma etches the surface of the emitter away, and simultaneously diffuses into the silicon and increase the bulk lifetime. Both minority carrier lifetime and etch rate depend on the grain orientation. Hydrogen diffusion is hindered by the high phosphorous concentration of the emitter, as shown on the SIMS profiles. Besides, SIMS profiles are revealing an anomalous behaviour of phosphorous, which diffuses into the silicon at temperatures as low as 3501C on (1 0 0) oriented grains.

Research paper thumbnail of Potential of quarterwave interference stacks for colored thermal solar collectors

Solar Energy, 2005

The architectural integration of thermal solar collectors into buildings is often limited by thei... more The architectural integration of thermal solar collectors into buildings is often limited by their black color and the visibility of tubes and corrugations of the absorber sheets. A certain freedom in color choice would be desirable, but the colored appearance should not cause excessive energy losses. Multilayered interference filters on the collector glazing can produce a colored reflection, hiding the corrugated metal sheet, while transmitting the non-reflected radiation entirely to the absorber. We investigate the potential of quarterwave stacks by simulation of their optical behavior, yielding the visible reflectance R VIS , the solar transmittance T sol , a figure of merit M = R VIS /R sol , and the CIE color coordinates. The necessary number of individual layers in the multilayer stack as well as the choice of refractive indices and thus of thin film materials are discussed. Finally, examples for realistic multilayer designs are proposed.

Research paper thumbnail of Deposition of micro crystalline silicon films using microwave plasma enhanced chemical vapor deposition

Research paper thumbnail of Review—Energy Autonomous Wearable Sensors for Smart Healthcare: A Review

Journal of The Electrochemical Society

Energy Autonomous Wearable Sensors (EAWS) have attracted a large interest due to their potential ... more Energy Autonomous Wearable Sensors (EAWS) have attracted a large interest due to their potential to provide reliable measurements and continuous bioelectric signals, which help to reduce health risk factors early on, ongoing assessment for disease prevention, and maintaining optimum, lifelong health quality. This review paper presents recent developments and state-of-the-art research related to three critical elements that enable an EAWS. The first element is wearable sensors, which monitor human body physiological signals and activities. Emphasis is given on explaining different types of transduction mechanisms presented, and emerging materials and fabrication techniques. The second element is the flexible and wearable energy storage device to drive low-power electronics and the software needed for automatic detection of unstable physiological parameters. The third is the flexible and stretchable energy harvesting module to recharge batteries for continuous operation of wearable sensors. We conclude by discussing some of the technical challenges in realizing energy-autonomous wearable sensing technologies and possible solutions for overcoming them.

Research paper thumbnail of Towards Low Cost and Low Temperature Capacitive CO2 Sensors Based on Amine Functionalized Silica Nanoparticles

Nanomaterials

Hybrid materials based on inorganic particles and an organic polymer were developed and used as a... more Hybrid materials based on inorganic particles and an organic polymer were developed and used as an efficient sensing material for carbon dioxide (CO2). The sensing material consists of fumed silica that is functionalized with an organic polymer, polyethylenimine, by means of the impregnation method. The organic polymer is effectively immobilized around the silica nanoparticles and confirmed by infrared spectroscopy. Thermogravimetric analysis proves the thermal stability of the sensing material. CO2 capacitive sensors operating at temperatures lower than 70 °C were fabricated by depositing a thin layer of hybrid sensing material on interdigitated gold electrodes. Impedance spectroscopy explored the sensing capability of the hybrid organic–inorganic material towards CO2 in the presence of different relative humidity levels, as well as its stability and reversibility. This strategy to couple organic and inorganic materials as a sensing layer for CO2 paves the way for the design of a l...

Research paper thumbnail of An Approach to Reduce Greenhouse Gases in the Semiconductor Industry Using F2 Dissociated in Plasma for CVD Chamber Cleaning

Applied Sciences

The gases used in industrial cleaning processes are considered greenhouse gases with a high globa... more The gases used in industrial cleaning processes are considered greenhouse gases with a high global warming potential (GWP). It is important to provide a viable alternative chemical vapor deposition (CVD) cleaning gas that is capable of removing efficiently deposited layers on the CVD chamber inner wall and other parts of the apparatus. The cleaning gas has to be environmental friendly in order to avoid accentuation of the global warming phenomena. Besides that, the alternative cleaning gas should be compatible with the existing gas delivery system and the CVD equipment that is already used by industrial companies. Only by fulfilling the three requirements mentioned above is it possible to replace the well-established cleaning gases. In this project, an F 2-gas mixture for the in-situ cleaning of CVD chambers has been studied and compared with conventional cleaning methods. The conventional cleaning process is defined as a cleaning procedure using either C 2 F 6 in RF plasma discharge or NF 3 in remote plasma discharge.

Research paper thumbnail of Enzymatic Sensor Based on Dye Sensitized TiO2 Electrode for Detection of Catechol in Water

Research paper thumbnail of Method to Study Water Diffusion into Polymers

Proceedings

We designed and realized a low cost relative humidity (RH) capacitive sensor having an interdigit... more We designed and realized a low cost relative humidity (RH) capacitive sensor having an interdigitated transducer coated with a cheap sensing material working at room temperature (polyimide). Thermally perturbed diffusion of water molecules into the polyimide layer is studied by heating the sensor locally and measuring the sensor capacitance change. The swelling and deswelling model is applied to determine the time constant of involved processes. This simple method, using an evaluation kit developed by our group, to measure the sensor capacitance and to study the diffusion process of water molecules into polyimide could be generalized to analyze the gas diffusion processes into polymer based sensing layer generally used in the field of gas chemical sensors.

Research paper thumbnail of Capacitive CO2 Sensor

Proceedings

The objective of the present paper is to provide a concept for a chemical sensor having a small s... more The objective of the present paper is to provide a concept for a chemical sensor having a small size, a low power consumption and a high reliability for sensing CO2 under different humidity levels at atmospheric pressure, while maintaining a long term stability under working conditions. A high temperature regeneration process of the sensing layer is unneeded to ensure a long term stability of the sensing material. This objective is achieved by using a hybrid organic-inorganic nanomaterial, consisting of inorganic nanoparticles functionalized with an amine-based polymer.

Research paper thumbnail of Multilayer films for coloured glazed solar collectors

Research paper thumbnail of Simultaneous bulk hydrogen passivation and selective emitter formation assisted by ECR-plasma applied to industrial mc-Si solar cells

Conference Record of the Twenty-Eighth IEEE Photovoltaic Specialists Conference - 2000 (Cat. No.00CH37036), 2000

ABSTRACT The authors present a new way of realising a selective emitter, using the simultaneous e... more ABSTRACT The authors present a new way of realising a selective emitter, using the simultaneous etching and hydrogenation properties of the ECR-H 2 plasma (electron cyclotron resonance hydrogen plasma). The impact of the H2-plasma on multicrystalline silicon (POLIX TM) is studied in terms of bulk lifetime. It is shown that during the hydrogenation step, the ECR-plasma etches back the emitter surface at a rate of about 100 nm/hour. Besides, on sheet resistance mappings, they have observed that the etch rate depends on grain orientation. The etch-back is used to form the selective emitter during the hydrogenation process. Solar cells were realised using the screen-printed contacts as a mask against the plasma effect. The short circuit current can gain more than 1 mA/cm2, the gain coming from the whole spectral range, this due to the less recombinating surface and the hydrogenated bulk material

Research paper thumbnail of Coatings for colored glazed thermal solar collectors and solar active glass facades

Research paper thumbnail of Towards colored glazed thermal solar collectors

Research paper thumbnail of Designing thin film multilayers for colored glazed thermal collectors

Research paper thumbnail of Photoemission study of the iron-induced chemical reduction of silicon native oxide

Surface Science, 2003

Samples consisting of Fe deposited onto a Si wafer covered with its native oxide layer have been ... more Samples consisting of Fe deposited onto a Si wafer covered with its native oxide layer have been studied by photoelectron spectroscopy for different Fe coverages and different deposition techniques involving different kinetic energies for the deposited Fe atoms. We find that the Fe atoms are buried into the substrate even for low kinetic energy techniques, and that a reduction of the Si oxide concomitant with an oxidation of the Fe occurs. This reaction can be assisted by increasing the kinetic energy of the Fe atoms.

Research paper thumbnail of Thin film multilayer design types for colored glazed thermal solar collectors

Solar Energy Materials and Solar Cells, 2005

Multilayered interference filters of dielectric thin films have been designed for the application... more Multilayered interference filters of dielectric thin films have been designed for the application as energy-efficient coloration of collector cover glasses. The optical behavior of the designed multilayers is analyzed by computer simulations yielding the CIE color coordinates, the relative luminosity, the degree of solar transmission, and a figure of merit which is a measure for the energy effectiveness of the coloration. A high performance should be achieved with a number of individual layers reasonable for large-scale deposition. Constraints on the refractive index of the dielectric films are given by the availability of suitable thin film materials. The challenge lies in finding the best combination of material choice and layer thicknesses. We describe several types of multilayer designs for which the computer simulations yield promising results.

Research paper thumbnail of Multilayered Al2O3/SiO2 and TiO2/SiO2 coatings for glazed colored solar thermal collectors

Solar Energy Materials and Solar Cells, 2005

Our aim is to study the possibility of integrating dielectric multilayer films deposited on glass... more Our aim is to study the possibility of integrating dielectric multilayer films deposited on glass substrates as a colored glazed cover for thermal solar collectors and building faces. The cover glass should ideally reflect only a narrow band of visible light while transmitting the rest of the sunlight spectrum to minimize energy loss. A compromise between the visible reflectance and the solar transmission has to be found. In our multilayer interference filters, we used two materials having, respectively, a high and a low refractive index. We studied two cases: Al 2 O 3 / SiO 2 and TiO 2 /SiO 2. The thin films were deposited by reactive magnetron sputtering. In situ XPS characterizations were carried out for each film by transferring the sample from the deposition chamber to an ultra-high vacuum analysis chamber without breaking the vacuum. The growth rate of TiO 2 , SiO 2 and Al 2 O 3 single layers on Si substrates were monitored by in situ laser reflectometry. Spectroscopic ellipsometry was used to determine the optical constants and the thicknesses of every individual dielectric layer. Reflectivity measurements of the experimentally realized dielectric multilayers deposited on glass substrates confirmed their transparency and their good accordance with the simulation. The multilayers were also characterized by their solar transmission, visible reflectance and a factor of merit.

Research paper thumbnail of Towards coloured glazed thermal solar collectors

Solar Energy Materials and Solar Cells, 2004

ABSTRACT Multilayers of TiO2 and SiO2 dielectric coatings deposited by reactive sputtering have b... more ABSTRACT Multilayers of TiO2 and SiO2 dielectric coatings deposited by reactive sputtering have been characterized by X-ray photoelectron spectroscopy, in situ real-time laser reflectometry, spectroscopic ellipsometry and spectrophotometry. Measurements have been performed on individual dielectric layers of TiO2, SiO2 and multilayers. The experiments show a good agreement between the different techniques. Optical properties can be modelled properly using a Cauchy dispersion model. The optical constants of an individual layer are confirmed by the optical measurements on more complex multilayer structures. Reflectivity of the three-layer films fulfils the requirements for a first step towards coloured glazed thermal solar collectors.

Research paper thumbnail of Electrical properties of multicrystalline silicon produced by electromagnetic casting process: Degradation and improvement

Solar Energy Materials and Solar Cells, 2001

The electrical properties of boron-doped multicrystalline silicon for photovoltaic applications, ... more The electrical properties of boron-doped multicrystalline silicon for photovoltaic applications, elaborated by the cold crucible pulling process, are studied by the photoconductivity decay method and the electron beam-induced current measurement technique. The bulk lifetime mapping of the minority carriers in the as-grown silicon wafers is drawn up using both the techniques. Moreover, the consequence of phosphorus doping on the recombination

Research paper thumbnail of Comparison of phosphorus gettering for different multicrystalline silicon

Solar Energy Materials and Solar Cells, 2002

The influence of a rapid thermal treatment on multicrystalline silicon produced by ElectroMagneti... more The influence of a rapid thermal treatment on multicrystalline silicon produced by ElectroMagnetic Casting process (Emix® and Sitix®) and by directional solidification (Polix®), are investigated and compared in this paper. We have studied bifacial diffusion of phosphorus in this multicrystalline silicon and its gettering effect on the minority carrier lifetime measured by the photoconductivity decay technique. The diffusion is carried

Research paper thumbnail of Phosphorous emitter etch back and bulk hydrogenation by means of an ECR-hydrogen plasma applied to form a selective emitter structure on mc-Si

Solar Energy Materials and Solar Cells, 2002

In this paper, we study the effect of hydrogen-electron cyclotron resonance plasma (ECR plasma) o... more In this paper, we study the effect of hydrogen-electron cyclotron resonance plasma (ECR plasma) on the phosphorous-doped emitter of a solar cell based on multicrystalline silicon (POLIX s). The purpose of this experiment is to realise a selective emitter structure, using the front metal contacts as a mask. We show that hydrogen plasma etches the surface of the emitter away, and simultaneously diffuses into the silicon and increase the bulk lifetime. Both minority carrier lifetime and etch rate depend on the grain orientation. Hydrogen diffusion is hindered by the high phosphorous concentration of the emitter, as shown on the SIMS profiles. Besides, SIMS profiles are revealing an anomalous behaviour of phosphorous, which diffuses into the silicon at temperatures as low as 3501C on (1 0 0) oriented grains.

Research paper thumbnail of Potential of quarterwave interference stacks for colored thermal solar collectors

Solar Energy, 2005

The architectural integration of thermal solar collectors into buildings is often limited by thei... more The architectural integration of thermal solar collectors into buildings is often limited by their black color and the visibility of tubes and corrugations of the absorber sheets. A certain freedom in color choice would be desirable, but the colored appearance should not cause excessive energy losses. Multilayered interference filters on the collector glazing can produce a colored reflection, hiding the corrugated metal sheet, while transmitting the non-reflected radiation entirely to the absorber. We investigate the potential of quarterwave stacks by simulation of their optical behavior, yielding the visible reflectance R VIS , the solar transmittance T sol , a figure of merit M = R VIS /R sol , and the CIE color coordinates. The necessary number of individual layers in the multilayer stack as well as the choice of refractive indices and thus of thin film materials are discussed. Finally, examples for realistic multilayer designs are proposed.