Monday, July 28, 2008
Academia Europea "European Academy of Science and Art"
Academia Europea "European Academy of Science and Art"
Monday, July 21, 2008
Professor "Michel Che"
This Week Professor "Michel Che" with his wife will be our university's guest. As Professor Anpo has a vast scientific communication around the world he has many contribution with Distinguished Scientist especially in the field of Catalysis , Photocatalysis and Nanotechnology.
Professor Che is an active scientist in the field of Catalysis and published about 400 Scientific papers. Find more information about him in Wikipedia online encyclopedia.
Thursday, July 17, 2008
What do you think about it?
I found a detailed news about a New car Here in Osaka Near me that can work just with pure water (yes just Water) and nothing else. If any person can explain the scientific details I will be grateful. Because it is very complicated and I believe it is impossible.
This car runs on hydrogen made on board the car. No high pressure storage tank needed. This is the way to go.
watch the Video here:
## On demand hydrogen power car
## Gore challenges US to ditch oil
Also in Persian:
پایان وابستگی آمریکا به نفت ظرف 10 سال ##
This car runs on hydrogen made on board the car. No high pressure storage tank needed. This is the way to go.
watch the Video here:
## On demand hydrogen power car
## Gore challenges US to ditch oil
Also in Persian:
پایان وابستگی آمریکا به نفت ظرف 10 سال ##
Sunday, July 13, 2008
THIN FILM GROWTH PROCESS
Any Thin-film deposition process involves three main steps:
1. Production of the appropriate atomic, molecular, or ionic species.
2. Transport of these species to the substrate through a medium.
3. Condensation on the substrate, either directly or via a chemical and/or electrochemical reaction, to form a solid deposit.
Formation of a thin film takes place via nucleation and growth processes. The general picture of the step-by-step growth process emerging from the various experimental and theoretical studies can be presented as follows:
1. The unit species, on impacting the substrate, lose their velocity component normal to the substrate (provided the incident energy is not too high) and are physically adsorbed on the substrate surface.
2. The adsorbed species are not in thermal equilibrium with the substrate initially and move over the substrate surface. In this process they interact among themselves, forming bigger clusters.
3. The clusters or the nuclei, as they are called, are thermodynamically unstable and may tend to desorb in time, depending on the deposition parameters. If the deposition parameters are such that a cluster collides with other adsorbed species before getting desorbed, it starts growing in size. After reaching a certain critical size, the cluster becomes thermodynamically stable and the nucleation barrier is said to have been overcome. This step involving the formation of stable, chemisorbed, critical-sized nuclei is called the nucleation stage.
4. The critical nuclei grow in number as well as in size until a saturation nucleation density is reached. The nucleation density and the average nucleus size depend on a number of parameters such as the energy of the impinging species, the rate of impingement, the activation energies of adsorption, desorption, thermal diffusion, and the temperature, topography, and chemical nature of the substrate. A nucleus can grow both parallel to the substrate by surface diffusion of the adsorbed species, and perpendicular to it by direct impingement of the incident species.
In general, however, the rate of lateral growth at this stage is much higher than the perpendicular growth. The grown nuclei are called islands.
5. The next stage in the process of film formation is the coalescence stage, in which the small islands start coalescing with each other in an attempt to reduce the substrate surface area. This tendency to form bigger islands is termed agglomeration and is enhanced by increasing the surface mobility of the adsorbed species, by, for example, increasing the substrate temperature. In some cases, formation of new nuclei may occur on areas freshly exposed as a consequence of coalescence.
6. Larger islands grow together, leaving channels and holes of uncovered substrate. The structure of the films at this stage changes from discontinuous island type to porous network type. Filling of the channels and holes forms a completely continuous film.
The growth process thus may be summarized as consisting of a statistical process of nucleation, surface-diffusion controlled growth of the three-dimensional nuclei, and formation of a network structure and its subsequent filling to give a continuous film. Depending on the thermodynamic parameters of the deposit and the substrate surface, the initial nucleation and growth stages may be described as
(a) Island type, called Volmer-Weber type,
(b) Layer type, called Frank-van der Merwe type, and
(c) Mixed type, called Stranski-Krastanov type.
1. Production of the appropriate atomic, molecular, or ionic species.
2. Transport of these species to the substrate through a medium.
3. Condensation on the substrate, either directly or via a chemical and/or electrochemical reaction, to form a solid deposit.
Formation of a thin film takes place via nucleation and growth processes. The general picture of the step-by-step growth process emerging from the various experimental and theoretical studies can be presented as follows:
1. The unit species, on impacting the substrate, lose their velocity component normal to the substrate (provided the incident energy is not too high) and are physically adsorbed on the substrate surface.
2. The adsorbed species are not in thermal equilibrium with the substrate initially and move over the substrate surface. In this process they interact among themselves, forming bigger clusters.
3. The clusters or the nuclei, as they are called, are thermodynamically unstable and may tend to desorb in time, depending on the deposition parameters. If the deposition parameters are such that a cluster collides with other adsorbed species before getting desorbed, it starts growing in size. After reaching a certain critical size, the cluster becomes thermodynamically stable and the nucleation barrier is said to have been overcome. This step involving the formation of stable, chemisorbed, critical-sized nuclei is called the nucleation stage.
4. The critical nuclei grow in number as well as in size until a saturation nucleation density is reached. The nucleation density and the average nucleus size depend on a number of parameters such as the energy of the impinging species, the rate of impingement, the activation energies of adsorption, desorption, thermal diffusion, and the temperature, topography, and chemical nature of the substrate. A nucleus can grow both parallel to the substrate by surface diffusion of the adsorbed species, and perpendicular to it by direct impingement of the incident species.
In general, however, the rate of lateral growth at this stage is much higher than the perpendicular growth. The grown nuclei are called islands.
5. The next stage in the process of film formation is the coalescence stage, in which the small islands start coalescing with each other in an attempt to reduce the substrate surface area. This tendency to form bigger islands is termed agglomeration and is enhanced by increasing the surface mobility of the adsorbed species, by, for example, increasing the substrate temperature. In some cases, formation of new nuclei may occur on areas freshly exposed as a consequence of coalescence.
6. Larger islands grow together, leaving channels and holes of uncovered substrate. The structure of the films at this stage changes from discontinuous island type to porous network type. Filling of the channels and holes forms a completely continuous film.
The growth process thus may be summarized as consisting of a statistical process of nucleation, surface-diffusion controlled growth of the three-dimensional nuclei, and formation of a network structure and its subsequent filling to give a continuous film. Depending on the thermodynamic parameters of the deposit and the substrate surface, the initial nucleation and growth stages may be described as
(a) Island type, called Volmer-Weber type,
(b) Layer type, called Frank-van der Merwe type, and
(c) Mixed type, called Stranski-Krastanov type.
Monday, July 7, 2008
Saturday, July 5, 2008
Sputtering
The Sputtering process is a key technology for material engineering in the twenty-first century.
Sputtering had been observed for the first time about 150 years ago in a discharge tube by Bunsen and Grove. Since then the basic level of understanding of the sputtering phenomena has been refined. The applications of sputtering, however, are still being developed on a daily basis. Sputtering deposition and sputtering etching have become common manufacturing processes for a wide variety of industries. First and foremost is the electronics industry, which uses sputtering technology to produce integrated circuits and magneto-optical recording media. This book describes many of the sputtering applications that are relevant to electronics.
Sputtering processes are also present in many other disparate areas. For example, sputter deposition is used to coat the mirrorlike reflective windows in many buildings. The hard coating of a machine tool is a well-known application
of sputtering.
Sputtering is essential for the creation of new materials such as diamond thin films, high-Tc superconductors, and ferroelectric and magnetic materials like those used in random access memories.
Nanometer materials are also provided by sputtering. It is important that the sputtering process is considered an environmentally benign production technology.
In the last ten years, radical progress has been seen in sputtering technology. For production, an example is the high-rate sputtering technology using pulsed DC/MF dual-magnetron sputtering for coating large areas like window glass. Another production technology is the sputter-etching of deep trench structures using plasma-assisted long-throw magnetron sputtering systems. At the basic research level, epitaxial processing of complex oxides such as layered perovskite for high-Tc superconductors and ferroelectric superlattices of perovskites at the nanometer level were extensively studied, and commercial sputtering systems were developed.
Sputtering had been observed for the first time about 150 years ago in a discharge tube by Bunsen and Grove. Since then the basic level of understanding of the sputtering phenomena has been refined. The applications of sputtering, however, are still being developed on a daily basis. Sputtering deposition and sputtering etching have become common manufacturing processes for a wide variety of industries. First and foremost is the electronics industry, which uses sputtering technology to produce integrated circuits and magneto-optical recording media. This book describes many of the sputtering applications that are relevant to electronics.
Sputtering processes are also present in many other disparate areas. For example, sputter deposition is used to coat the mirrorlike reflective windows in many buildings. The hard coating of a machine tool is a well-known application
of sputtering.Sputtering is essential for the creation of new materials such as diamond thin films, high-Tc superconductors, and ferroelectric and magnetic materials like those used in random access memories.
Nanometer materials are also provided by sputtering. It is important that the sputtering process is considered an environmentally benign production technology.
In the last ten years, radical progress has been seen in sputtering technology. For production, an example is the high-rate sputtering technology using pulsed DC/MF dual-magnetron sputtering for coating large areas like window glass. Another production technology is the sputter-etching of deep trench structures using plasma-assisted long-throw magnetron sputtering systems. At the basic research level, epitaxial processing of complex oxides such as layered perovskite for high-Tc superconductors and ferroelectric superlattices of perovskites at the nanometer level were extensively studied, and commercial sputtering systems were developed.
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