Semiconductor Physics and Devices: Solar Cell

Solar cells are devices that convert photon energy into electricity. There are several types of solar cells regarding the materials which are used. The common structure of solar cell is configured by p-n junction where electron-hole pair generation takes place, and electrodes to transfer the electrons. There are other components installed in some solar cells in order to improve efficiency such as inserting intrinsic semiconductor in enlarge the area of photocurrent generation or reflector to enhance photon energy. The example of organic and inorganic solar cells is presented in Fig. 1. The mechanism of power generation of solar cells is due to photovoltaic effect  which explains that light of certain wavelengths is able to ionize the atoms in semiconductor materials and the internal electric field produced by the p-n junction separates some of the positive charges ("holes") from the negative charges (electrons) which then are transferred to the electrodes. Here, the band gap between p-type and n-type semiconductors determines the specific absorbance of light.

QA on Delectric Materials

Q1. Describe the definition of dielectric materials

Dielectric materials are electrical insulators which can be easily polarized by external electric field.  The presence of electric field results in charges re-arrangement in which the positive charges are displaced toward the field whereas negative charges are in opposite direction so called dielectric polarization. They are categorized as electrical insulator since there is no field induced-charges flow as it happens on conductor. This is due to large energy band gap and no free electron exists at conduction band. Closely seeing to the atomic model, the external electric field will distort electron cloud surrounding nucleus and give rise to electric dipole.

Introduction to Biosensor

      A biosensor is defined as a detecting device that combines a transducer with a biologically sensitive and selective component. When a specific target molecule interacts with the biological component, a signal is produced, at transducer level, proportional to the concentration of the substance. Therefore biosensors can measure compounds present in the environment, chemical processes, food and human body at low cost if compared with traditional analytical techniques. According to the receptor type, biosensors can be classified as enzymatic biosensors, genosensors, immunosensors, etc. Biosensors can be also divided into several categories based on the transduction process, such as electrochemical, optical, piezoelectric, and thermal/calorimetric biosensors.

Material Surface Analysis with X-Ray Photoelectron Spectroscopy (XPS)

       The XPS technique is used to investigate the chemistry at the surface of a sample. The basic mechanism behind an XPS instrument is illustrated in below picture, where photons of a specific energy are used to excite the electronic states of atoms below the surface of the sample. Electrons ejected from the surface are energy filtered via a hemispherical analyzer (HSA) before the intensity for a defined energy is recorded by a detector. Since core level electrons in solid-state atoms are quantized, the resulting energy spectra exhibit resonance peaks characteristic of the electronic structure for atoms at the sample surface. While the x-rays may penetrate deep into the sample, the escape depth of the ejected electrons is limited. That is, for energies around 1400 eV, ejected electrons from depths greater than 10nm have a low probability of leaving the surface without undergoing an energy loss event, and therefore contribute to the background signal rather than well defined primary photoelectric peaks.

Are We Safe from Nuclear Radiation?

       In about a week ago, we were surprised by nuclear crisis on Fukushima Daiichi Complex, Japan since hit by earthquake 8.9 R.S. It is worried if the radiation of radioactive substances will blow up and contaminate many people affecting the health. But, basically we are exposed to nuclear radiation every day of our lives. Some of this radiation is from natural sources, and some results from human activity. Natural sources include cosmic radiation from space, radiation from lighter, unstable nuclei produced by the bombardment of the atmosphere by cosmic radiation, and radiation from heavy, unstable nuclei produced by the decay of a few long-lived nuclides in the earth’s crust. Artificial sources include medical procedures, commercial products that contain radioactive materials, and fallout from nuclear testing.

How the Particles Enter Cell?

      An alternative solution of cancer treatment is the cellular treatment that allows the medicine invades into cancer cell and disturbs metabolism to kill the cell. In magnetic hyperthermia cancer treatment, the nanoparticles are injected into the abnormal tissue, by subjected with high frequency AC magnetic field, the cancer cells are heated. This kind of cellular treatment will be more effective if the amounts of nanoparicles that enter the cells are bigger. Since the amounts are greater, the heat generated by superparamagnetism effect of magnetic nanoparticles increases and will be uniformly distributed inside the cell.

        Molecules and particles will enter the cell via cell membrane. The size also determines how they can pass through the membrane. If the diameter of nanoparticles is big, they cannot enter passively, and only stay in interstitial fluid. Although the hyperthermia process will still go on, the effect is less effective than the nanoparticles stay in plasma cell. Since the transport via cell membrane becomes one of many considerations in nanomagnetic design, the review about cellular membrane transport is needed.

Image Processing: Getting Some Information From An Image (Part 2)

       Pixel operation is operation of an image where each pixel's intensity value is modified. The modification/transformation depends solely on its previous value, regardless of its position and other pixels value. Some image operation in this category is brightness modification, contrast enhancement, color inversion (negation), and thresholding operation.

       Pixel operation is done by transforming each pixel value to new value according to a transformation function, known as gray-scale transformation (GST) function. This function maps the gray-level input (Ki) to a new gray-level output (Ko). In general, a GST function can be expressed as:

Image Processing: Getting Some Information From An Image (Part 1)

        In infrared imaging, images are source of primary data processed to obtain useful information of temperature distribution. In some cases, the data gathering is not about single sampling but continuous sampling that shows temperature varying in unit time. To analyze and get the correspondence between image and temperature distribution, image processing method is used. Image processing deals with color manipulation, pixel-by-pixel operation, even frame-by-frame operation that can be associated in degree of temperature.

A Great Instrument To Atomize Liquid: Ultrasonic Vibrator

        Now, in nanotechnology era, the smallest sized thing is regarded. In domain of about 10^-9 m or 10 Å size, material becomes unique. We have already known the implementation of SPIO (small particle iron oxides which have size distribution up to 10 nm) in biomedical application such magnetic hyperthermia, because they have unique size effect called superparamagnetism. Since size becomes important parameter in nanomaterial design, the researchers are urged to find best method to obtain finest result of nanomaterial synthesis, throughout chemical approaches, mechanical approaches even acoustical approaches. One of the best methods is ultrasonic atomization. 

         The applications of ultrasonic atomization for the generation of aerosol sprays are growing due to its capability for producing very small droplets with very narrow size distributions. The droplet size depends on the ultrasonic frequency, and hence it is possible to generate droplets in the micron range by using MHz-order driving frequencies. With higher frequencies, capillary waves are excited on the free surface primary drop at shorter wavelengths; destabilization of these waves then results in smaller atomized droplets. Nevertheless, ultrasonic atomizers are limited by a maximum frequency of around 1 MHz, due to the limitations of the piezoelectric material.

Let's Do Experiment Using XRD: How to Interpret the Diffractogram

      Basically, XRD (X-Ray Powder Diffraction), as a nondestructive technique has some functions for identifying crystalline phases and orientation, determining structural properties (lattice parameters, strain, grain size, phase composition, thermal expansion, etc), measuring thickness of thin films and multi layers, determining atomic arrangement. Thus, XRD is most widely used for the identification of unknown crystalline materials (e.g. minerals, inorganic compounds). Determination of unknown solids is critical to studies in geology, environmental science, material science, engineering and biology.

       In crystallography, the terms crystal system, crystal family, and lattice system each refer to one of several classes of space groups, lattices, point groups, or crystals. Informally, two crystals tend to be in the same crystal system if they have similar symmetries, though there are many exceptions to this. Space groups and crystals are divided into 7 crystal systems according to their point groups, and into 7 lattice systems according to their Bravais lattices. Five of the crystal systems are essentially the same as five of the lattice systems, but the hexagonal and trigonal crystal systems differ from the hexagonal and rhombohedral lattice systems.

        Doing experiment using XRD takes some procedural activities to achieve the objectives. Collecting, analyzing, and interpreting activities should be done by the researchers.

Nanoparticles Characterization Using AFM

        Nanoparticles, a unique subset of the broad field of nanotechnology, include any type of particle with at least one dimension of less than 500 nanometers. Nanoparticles play an important role in a wide variety of fields including advanced materials, pharmaceuticals, and environmental detection and monitoring.
        The atomic force microscope (AFM) is ideally suited for characterizing nanoparticles. It offers the capability of 3D visualization and both qualitative and quantitative information on many physical properties including size, morphology, surface texture and roughness. Statistical information, including size, surface area, and volume distributions, can be determined as well. A wide range of particle sizes can be characterized in the same scan, from 1 nanometer to 8 micrometers. In addition, the AFM can characterize nanoparticles in multiple mediums including ambient air, controlled environments, and even liquid dispersions.

Infrared Thermal Imaging: See The Unseen

       Infrared thermography also called infrared thermal imaging uses thermal imagers or Infrared imaging cameras. This technique is widely used in many application fields, such as analyzing component stress in PCB, surveillance affairs, monitoring body temperature etc. Infrared thermal imaging becomes effective method as monitoring tool since every matter radiates thermal energy. In bioengineering application, this method can be used to monitor the temperature distribution of human body in hyperthermia treatment. By monitoring, the researcher can control heat distribution to specific localization in disease area.

The Spectrum

       When the sun goes down and the other sources of illumination are removed, there is no light to be reflected and most mammals, especially, cannot see anything. The unaided human eye cannot see infrared radiation, but the radiation is always present. It is heat or thermal radiation in a portion of the Electromagnetic (EM) spectrum to which our eyes do not respond. Our bodies respond to infrared, if it is intense enough, by feeling warmed, or sometimes, cooled.

高速デジタルシステム: The Importance of Interconnect Design

          The speed of light is just too slow. Commonplace, modern, volume-manufactured digital designs require control of timings down to the picosecond range. The amount of time it takes light from your nose to reach your eye is about 100 picoseconds (in 100 ps, light travels about 1.2 in.). This level of timing must not only be maintained at the silicon level, but also at the physically much larger level of the system board, such as a computer motherboard. These systems operate at high frequencies at which conductors no longer behave as simple wires, but instead exhibit high-frequency effects and behave as transmission lines that are used to transmit or receive electrical signals to or from neighboring components. If these transmission lines are not handled properly, they can unintentionally ruin system timing. Digital design has acquired the complexity of the analog world and more. However, it has not always been this way. Digital technology is a remarkable story of technological evolution. It is a continuing story of paradigm shifts, industrial revolution, and rapid change that is unparalleled. Indeed, it is a common creed in marketing departments of technology companies that "by the time a market survey tells you the public wants something, it is already too late."

化学プロセス: Amine Gas Treating

A. Introduction

         Amine gas treating refers to a group of processes that use aqueous solutions of various amines to remove hydrogen sulfide (H₂S) and carbon dioxide (CO₂) from gases. It is a common unit process used in refineries, petrochemical plants, natural gas processing plants and other industries. The process is also known as Acid gas removal and Gas sweetening. Processes within oil refineries or natural gas processing plants that remove hydrogen sulfide and/or mercaptans are commonly referred to as sweetening processes because they results in products which no longer have the sour, foul odors of mercaptans and hydrogen sulfide.

      

Observing through Confocal Laser Scanning Microscopy

Problem Background

         Microscopy is term to examine or observe the small thing such as biological tissues, microbacteries, or other particulate matter, that can be seen using naked-eye. The main goal of microscopy is to create image as well as the real object so that resolution of image becomes main consideration. In conventional microscopy, it is still less resolution as we can see 3D-like image. Some of causes are confocal aperture, residual optical aberration and pupil illumination (Figure 1). So, it becomes problem how to filter the ray from object so that on from focal point of objective lens can be process.

Figure 1 Consideration in Microscopy

能動騒音制御: Wiping Up Unwanted Sound

騒音は辞書などで調べると，「日常生活の心の平静をかき乱す、不愉快で不必要に大きな音。」と定義されています。したがって、図書館内での話し声や隣の部屋から聞こえてくる音楽、また消防車・救急車のサイレンなども、人によっては騒音と言えるでしょう。とすれば、騒音は私たちにとって非常に身近な存在なのです。

ところで、あなたは騒音を小さくするにはどうしたらよいと考えますか？耳栓をする。壁で音を遮る。吸音材を買ってくる。どれも効果的ではあるでしょう。しかし、これだけでは騒音を完全に除去することはできません。私たちは、これらとは全く別の方法で騒音を小さくする研究をしています。それは、能動騒音制御（アクティブノイズコントロール：ANC）です。

A Guide to Corossion Protection: コーティング

表面処理（ひょうめんしょり、surface treatment、surface finishing）は、めっきや塗装など、素材表面の性質を高めるために行われる機械工作法の一種。硬さ・耐摩耗性や潤滑性・耐食性や耐酸化性・耐熱性や断熱性・絶縁性・密着性・装飾性や美観などを向上させるのがおもな目的となる。 　材料技術の一分野で、加工、熱処理、溶接、鋳造などの材料プロセス技術分野と並立する存在である。

[www.wikipedia.org]

Underbody structural components are typically coated to provide a first line of defense against corrosion. For light truck frames, the two most common coatings are hot melt wax and electrocoat (E-coat). Paints are also used on current light truck frames. Conversion coatings enhance the adhesion of electrocoat or paint, and they are commonly used in conjunction with these two coating types. Many underbody structural components, such as front rails on passenger cars, are made from sheet steel precoated with a metallic coating, e.g., galvanized or galvanneal sheet steel. Autophoretic and powder coatings are also used on underbody structural components.

Electrostatic Discharge [静電放電]--Part 2

ESD Protection Methods

           To protect against ESD, a designer can either add the protection externally or choose ICs with high levels of protection built in. Protection circuitry includes metal-oxide varistors and silicon avalanche suppressors such as the TransZorb. These devices are effective but expensive (silicon avalanche protectors cost as much as $0.30 per line). External ESD protection also consumes valuable board area and adds capacitance to the I/O line.

          To overcome these limitations, manufacturers have repeatedly raised the level of ESD protection in their ICs. Maxim, for example, now provides ±15kV protection for RS-232 ICs, whether tested in accordance with IEC 1000-4-2 or the human body model.

 

Electrostatic Discharge [静電放電]--Part 1

私は電子工学製造会社で働きます。開発方法間に多い問題があります。そして、ESD は一般的な問題です。この主題は面白いですから、今日 私達はそれを話会っています。もしあなたはどんな質問があったら、それを分配しましょう。

Electrical Fast Transient [高速過渡電気]

EFT/ Burst テストことは 知っていますか? EFTテストも基本的なルールのEMC です。電子工学製造会社は製品を売る前にEFT テストを受けなければなりません。それじゃあ,時々 EFTテスト には問題があります。あなたが知りたい場合, この記事を読んでください... ^_^。