Semiconductors Essays - Semiconductor Device Fabrication

Semiconductors Silicon is the raw material most often used in integrated circuit (IC) fabrication. It is the second most abundant substance on the earth. It is extracted from rocks and common beach sand and put through an exhaustive purification process. In this form, silicon is the purist industrial substance that man produces, with impurities comprising less than one part in a billion. That is the equivalent of one tennis ball in a string of golf balls stretching from the earth to the moon. Semiconductors are usually materials which have energy-band gaps smaller than 2eV. An important property of semiconductors is the ability to change their resistivity over several orders of magnitude by doping. Semiconductors have electrical resistivities between 10-5 and 107 ohms. Semiconductors can be crystalline or amorphous. Elemental semiconductors are simple-element semiconductor materials such as silicon or germanium. Silicon is the most common semiconductor material used today. It is used for diode s, transistors, integrated circuits, memories, infrared detection and lenses, light-emitting diodes (LED), photosensors, strain gages, solar cells, charge transfer devices, radiation detectors and a variety of other devices. Silicon belongs to the group IV in the periodic table. It is a grey brittle material with a diamond cubic structure. Silicon is conventionally doped with Phosphorus, Arsenic and Antimony and Boron, Aluminum, and Gallium acceptors. The energy gap of silicon is 1.1 eV. This value permits the operation of silicon semiconductors devices at higher temperatures than germanium. Now I will give you some brief history of the evolution of electronics which will help you understand more about semiconductors and the silicon chip. In the early 1900's before integrated circuits and silicon chips were invented, computers and radios were made with vacuum tubes. The vacuum tube was invented in 1906 by Dr.Lee DeForest. Throughout the first half of the 20th century, vacuum tube s were used to conduct, modulate and amplify electrical signals. They made possible a variety of new products including the radio and the computer. However vacuum tubes had some inherent problems. They were bulky, delicate and expensive, consumed a great deal of power, took time to warm up, got very hot, and eventually burned out. The first digital computer contained 18,000 vacuum tubes, weighed 50 tins, and required 140 kilowatts of power. By the 1930's, researchers at the Bell Telephone Laboratories were looking for a replacement for the vacuum tube. They began studying the electrical properties of semiconductors which are non-metallic substances, such as silicon, that are neither conductors of electricity, like metal, nor insulators like wood, but whose electrical properties lie between these extremes. By 1947 the transistor was invented. The Bell Labs research team sought a way of directly altering the electrical properties of semiconductor material. They learned they could ch ange and control these properties by "doping" the semiconductor, or infusing it with selected elements, heated to a gaseous phase. When the semiconductor was also heated, atoms from the gases would seep into it and modify its pure, crystal structure by displacing some atoms. Because these dopant atoms had different amount of electrons than the semiconductor atoms, they formed conductive paths. If the dopant atoms had more electrons than the semiconductor atoms, the doped regions were called n-type to signify and excess of negative charge. Less electrons, or an excess of positive charge, created p-type regions. By allowing this dopant to take place in carefully delineated areas on the surface of the semiconductor, p-type regions could be created within n-type regions, and vice-versa. The transistor was much smaller than the vacuum tube, did not get very hot, and did not require a headed filament that would eventually burn out. Finally in 1958, integrated circuits were invented. By the mid 1950's, the first commercial transistors were being shipped. However research continued. The scientist began to think that if one transistor could be built within one solid piece of semiconductor material, why not multiple transistors or even an entire circuit. With in a few years this speculation became one solid piece of material. These integrated circuits(ICs) reduced the number of electrical interconnections required in a piece of electronic equipment, thus increasing reliability and speed. In contrast, the first digital electronic computer built with 18,000 vacuum tubes and weighed 50 tons,

Arabic Loanwords In English

Arabic Loanwords In English Arabic Loanwords In English Arabic Loanwords In English By Sharon The Arabic language has contributed hundreds of words to the English language by many different routes. Thats partly because in what my daughter likes to call the olden days (from around 700AD to the Middle Ages), the Arabic kingdoms had a great influence on Europe and the world. In part this was through colonisation, but there were also many great mathematicians, alchemists and astronomers. Of course, language development is not that simple. Not all the words that have entered English via Arabic originate from that language. Linguistically speaking, the Arabs borrowed as freely as they lent and their language included words originating from Spanish, Latin, Greek, Persian, Hebrew and many others. Many of the words start with the Arabic definite article al, which also appears in silent form without the l in words such as admiral. Heres a list of some of the common words that the Arabic language has bequeathed to English. admiral adobe alchemy via Greek alcohol the quintessence of earthly substances, originally from alchemy alcove algebra restoration of missing parts, later used in a 9th century mathematical book written by a Persian scientist whose name gave us algorithm almanac amber apricot arsenal factory assassin hashish user artichoke aubergine burnoose via Latin caliber carat via Greek checkmate coffee possibly from the name Kefa, where the coffee plant originates cotton divan elixir medicinal potion, via Greek gauze from the Persian for raw silk gazelle genie giraffe harem hashish henna jasmine from Arabic via French kohl lilac, from Persian for indigo lime loofah lute magazine storehouse mocha named after a city in Yemen monsoon mummy via Persian muslin nadir orange safari from Arabic via Swahili saffron sequin sugar tamarind tariff typhoon zenith zero Theres a fun quiz on Arabic loan words here and more words can be found here. Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Vocabulary category, check our popular posts, or choose a related post below:100 Words for Facial ExpressionsAbstract Nouns from AdjectivesPreposition Mistakes #3: Two Idioms

Taxation Assignment Example | Topics and Well Written Essays - 2500 words

Taxation - Assignment Example But at the same time you must keep in mind that starting out in self-employment poses many difficulties and you would have to work very hard with no guarantee of a regular income. But first of all you must assess for yourself if you are suitable for self-employment which requires total self commitment, ability to work long business hours which in turn requires physical and mental strength and, last but not the least, complete support from your family. Then you have to do market research to identify the opportunities available in your selected field. Since you are currently employed with a computer software company it is obvious you have the technical skills, but do you have the business skills to run your business. If you lack these skills you shall have to learn them fast from the information that I am about to provide you and from other sources. When you start out on your own in business you can do so as a sole trader, in partnership or by setting up a limited company. You have indicated that you wish to start your business as a sole trader, which means, you intend to set up your business on your own. Starting out as a sole trader is relatively easy and straightforward but if your business fails your liability is unlimited or in other words all your assets will be legally available and can be used to pay your creditors. If you intend to start your business from your home you are likely to be requiring Planning Permission. In case you are going to use one or two rooms in your home you would need to apply for a partial change of use from domestic to commercial purpose. In case you intend constructing a shed or additional room for your business you may require planning permission for which you shall have to contact your local authorities. Market research is very important before you set up your business in your chosen field but let me caution you that no amount of research will guarantee you success. However, your market

Dyadic partner Essay Example | Topics and Well Written Essays - 250 words

Dyadic partner - Essay Example When he is confused, he would also tug at his hair. He wears bright colored shirts like red, blue or green, when he is happy. But when he is excited about something and wants to share it with others, he sits upright and looks at other person’s eye. The body language of my partner is therefore vital means of communicating his mood. Whenever he comes in bright tee-shirt, I am much relaxed because I know that when he is happy, he works better with higher productive outcome! When I see him sitting upright on his chair, I know that he has some good news. But my worries are heightened when I see him tugging at his hair or find him looking away rather than talking to me. As I know that these behavior indicate his discomfort with the issue or his doubts which he is wary of sharing. At these times, I pick up the topic or issue that he is passionate about. When he gets involved and comfortable, I broach the subject of which he is wary about. This way, I am able to know his problem and resolve it so that he can focus on his

High School Life Essay Example for Free

High School Life Essay It was in the year 2009, I was a graduating elementary student back then, when our adviser talked to me, together with my fellow honor students, regarding our plans after graduation. The conversation included where we wanted to study in high school. Most of us said that a simple school will do, what’s important for us back then was to have a school. That simple. After a few words, our adviser said that there is prestigious school inviting us to study there. Our initial reaction was, of course, we have no money to pay for the tuition fee. But then, she said that we need not worry, because the school offers us 100% scholarship, with a weekly allowance. We were delighted by the news. Imagine being a scholar of Notre Dame of Greater Manila. That is something to be proud of. So we were scheduled for an exam. We were so nervous. After several days of waiting, the results came out. And I was the one chosen to be the scholar! When my mom told me the news, I was really overjoyed. It would be my first time to study in a private school, prestigious one even. I went to the school to arrange my requirements there. That was when I knew that I am a De Mazenod Lingap Talino (DMLT) scholar, who would enjoy 100% scholarship and weekly allowance. What a privilege! I also met there Mr. Diego Reyes, or Sir Jigs, as what the whole institution calls him, and Ma’am Sofie. They were the ones who helped me during my stay there as a scholar. My first year was tough. A lot of adjustments were done. Of course, I’m not used to having classmates who are techy and rich. They talked about this gadget and that gadget, which, in my previous school, is not an issue. I’m not used to seeing signature clothes and bags. So I didn’t know how I would approach them. I’m not rich as them. I am just a simple girl. Another reason why I’m afraid is because I thought I would not be accepted there. I am different, physically. Before the first day of school, I imagined the Damers teasing me and bullying me. And I imagined myself ignoring them, as if they don’t exist, and when I’m alone, I’d cry a lot just to let the feelings out. I thought I would be an outcast, a loner, weirdo in their eyes. But I was completely wrong. I gained a lot of friends, much many than I thought I’d have. My first impression of them was wrong. They are not like what I see in the movies, rich people who are arrogant and rude. They understand my situation. They are open-minded. They are real. They may tease me but that was only natural, I do not get offended. They are real, true friends. Of course, the teachers are a plus. I thought they would not like me, especially the Math teachers, because I’m really weak in that particular subject. I really like Math, but I guess the feeling ain’t mutual. Until now, I still use finger Math. I am extremely slow in solving problems. I thought Math teachers would lose their patience on me, ignore my presence in the cream class because they would think I don’t belong there, because I am a weakling. But then again, I was W-R-O-N-G. Math teachers in Notre are exactly the opposite of what I thought they would be. They are very kind, especially Mrs. Narciso, Ms.Padlan, Mr.R and Mr. Zuniga. They were the ones whom I spend my Math classes with during my entire stay in high school. They were the ones who taught me Math and helped me to improve my skills in that field. They showed me that I am not a weakling, I still have hope. Whoo. But of course, there were my second parents. Mrs. Mercado and Mrs. Asis who served as my mothers, and Mr. Saplagio as my dad. They were the ones whom I turn to and cry on whenever I have problems. And all of the teachers in Notre, who may seem terror and scary inside the classrooms, but outside, they are one of your bestest best friends. Being a scholar isn’t as easy as anyone thinks. It’s really tough maintaining your grades. It is stressing to think about your grades when they are going down. They say grades are just numbers, but I depend on those numbers. My scholarship depends on those numbers. I usually envy those who can just have fun while I am at my room studying even if there’s no exam. And of course, as a scholar, I should be a role model to others. I should take care of my reputation. But of course doing that is a bit hard. As the saying goes, â€Å"Character is what you are; reputation is what people think you are.† What if my character is different from my reputation? Yes, that happens all the time. But I just maintain my character and ignore those who pull me down by saying things about me behind my back. That made me stronger. Notre gave me a lot of experiences that I would not forget. Notre gave me people that I am thankful for. But of course, I would receive none of these if it wasn’t for the DMLT, for giving me this very wonderful opportunity to study in the institution. I am just a simple girl from a family who cannot afford the services of Notre. But because of Notre’s awareness of the students out there who are not financially able, yet deserving to have quality education, and it’s willingness to reach out to them, I was able to experience this once in a lifetime opportunity. Now, I am going to study in my dream school, the University in the Philippines, one of the most prestigious universities in the whole country. With the help of Notre, I was able to get this dream of mine. It equipped me with enough knowledge and skills to face the challenges ahead. My life in Notre had been stressful, yet everything was all worth it. For this, I would like to express my deep gratitude. Thank you, Notre Dame.

Comparing First Dates in Sottos Oranges and Wetherells The Bass, the

First Dates in Sotto's Oranges and Wetherell's The Bass, the River, and Shelia Mant Everyone is born with innocence and they gradually gain experience through lessons learned in life; some people may gain more that others. Not all lessons in life are dramatic or negative, some may be subtle, positive, or even life altering; however, no matter how small or big, they do alter one's perspective on things and help them to gain experience, which will be with them forever. These experiences may be gained through love, war, or death, but in some way or another they have changed one's point of view. The works "Oranges", written by Gary Sotto, and "The Bass, the River, and Shelia Mant", written by W.D. Wetherell, both tell about a boys first love and his first date. First loves and first dates is something that can be related to by everyone, whether boy or girl. These two works show that the outcome of a first date may not be what one expected, but in the end something more may be learned. In "The Bass, the River, and Shelia Mant", the speaker fell in love with a beautiful girl named Shelia Mant, which was the only thing that he loved more than fishing. He watched her everyday sunbathing on the dock. He watched her so much that he learned what mood she was in by the position she was laying. When the summer was almost over he got up enough nerve to ask her out. To his surprise she said yes. They went to see a band, however, since he was only fourteen they took a canoe. While rowing the canoe he had his fishing pole on the back, because he never left the house without it. Little did he know that Shelia thought fishing was dumb. So, during the entire canoe ride he is trying to hide the fishing pole, which is hanging o... ...h the speaker from "The Bass, the River, and Shelia Mant" did not have a great first date or love, he learned to be himself, not to change who he was so someone will like him. Although both speakers lost their innocence and gained experience in love and dating, they still have a lot more to learn in both. Innocence may be loss in a subtle or life altering way, negative or positive, but when all is said and done the experience gained will help one to succeed in life. Works Cited Lessing, Doris. "Through the Tunnel." Responding to Literature: Stories, Poems, Plays, and Essays. Fourth Edition. Ed. Judith A Stanford. Boston: McGrawHill, 2003. 860-867. Wetherell, W.D. "The Bass, the River, and Sheila Mant." Responding to Literature: Stories, Poems, Plays, and Essays. Fourth Edition. Ed. Judith A. Stanford. Boston: McGrawHill, 2003. 191-196.

African Negro Art Essay

In †Walker Evans: The Hungry Eye†, author Gilles Mora attempts to capture and represent every significant aspect of the photographer’s life and times via his art work. Evans was a Depression-era photographer with the Farm Security Administration and later editor of Fortune magazine. His work was featured in Time magazine and he was the first photographer to be given a solo show at New York’s Museum of Modern Art in 1938. In 1935, he had his first photograph display at the museum, a series he called â€Å"African Negro Art. † Evans did not initially set out to be a photographer, but ended up as part of a class of FSA photographers that included such greats as Dorothea Lange and Ansel Adams. He was born to well-to-do parents in St. Louis in 1903 and attend college in New York for a year before going to Paris to see the world. In 1927, he returned to the New York literary scene making friends with others who would go on to have a huge impact on his career. He first began taking photographs in 1928 and worked on Wall Street as a clerk to a stockbroker until the stock market crash in 1929. A year later his first photographs, of the Brooklyn Bridge, were published in a book of poetry by Hart Crane. During the Depression, Evans toured Cuba where he met Earnest Hemingway and worked for the Resettlement Administration in West Virginia before joining the FSA. He spent a great deal of time shooting American architecture as a manner of recording history and life and also spent 3 weeks living with sharecroppers in Alabama for a piece for Time magazine that James Agee was supposed to write. The piece did not meet Time’s standards, but he and Agee would publish the story and photos in 1941 in Let Us Now Praise Famous Men† Evans primarily used an 8† by 10† large format camera for his Depression era work, though he would switch to 35 mm in his later years. He is primarily known for his attempt to document life as it was without the influence of the photographer being felt in the photographs. This was, of course, impossible given the medium that he was using. The large size format combine with the film type meant that often his subjects would have to remain motionless for several minutes while the film was exposing. Still, even his staged photographs appeared to be accurate scenes of life in the South in the Depression. During World War II, Evans was a regular contributor to Time magazine and after the war he joined the staff of Fortune magazine where he was a regular contributor until 1965. In 1965, he left the magazine to become a professor of graphic design at Yale Univeristy in New Haven, Conn., where he remained until his death in 1975. Evans is best known for his Depression era work, but he also did several series after the war attempting to document American life. He did a series about American industrialization s shot from a moving train and about the people of New York City that he shot on the subway with a camera hidden in his coat. Evans is credited with having a strong influence on several American artists most notably Andy Warhol, who may have gotten the idea for his photo-booth series from work that Evans had done in a photo-booth. It is believed that Evans began experimenting with the use of photo booth imagery as early as 1929 in an attempt to divest himself from the role of artist in the taking of the photograph. Evans argued throughout most of his life in favor of the idea that photography should be a record of what was and not an artistic medium. Mora attempts to depict Evans’ work in a manner as closely as possible to the way they were originally presented, meaning some reproductions in the book are small and difficult to appreciate, but as a whole Evans’ body of work is amazing for its depiction of the human spirit.