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Abstract Conductor, semiconductor and insulator are defined by the characteristics of the energy band or the Fermi level. This paper identified some economic importance of conductor, semiconductor and insulator for sustainable human development. The paper concluded that these materials are very important to our technological development. It was suggested as one of the recommendations that government should make fund available to individual and institutions for businesses on these materials as they are naturally available in our soil. Introduction Conductor, semiconductor and insulator are defined by their energy band or by the Fermi level. The characteristic of the energy band distinguishes one from the other. We also use the position of the Fermi level to know if a material is conductor, semiconductor or insulator. Energy band is divided into three separate bands. The bands are valence band which is the lowest energy band, forbidden gap and conduction band. Valence band overlapped to conduction band in some metal like magnesium. Valence band is always filled with electrons while there is no electron in the forbidden gap. The presence of electrons in the conduction band will determine whether the material is conductor, semiconductor or insulator. Fermi level is the dividing line above which energy levels tend to be empty, and below which energy levels tend to be full. This Fermi level helps to define the insulation and conduction properties of materials. The world is growing fast in electronic and communication where we need different cables as conductors and insulators. Semiconductors are needed in the production of diode, resistors ceramics and microprocessor of integrated circuit. According to Familusi (2010), these materials are naturally present both In the soil and soil surface in our country and therefore, we should make proper use of them for a sustainable human development. Conductor Conductor is generally referred to as any material that allows electricity to pass through it. Most metals are found to be conductor. Electric charges are free to move in conductor (Halliday & Resnick, 1978). The energy band of conductor is divided into three bands for some metals. These bands are valence band, forbidden gap and conduction band. According to Aina (2007), some conductor like magnesium has a conduction band overlapping a valence band. The valence band is filled with electrons while conduction band is not filled but have few electrons that are used for conduction of electricity. In some metal there are very small forbidden gap between valence band and conduction band. The forbidden gap is very small to allow electron movement from valence band to conduction band. The Fermi level of conductor is in the middle of an allowed band (valence band). With Fermi level in the middle of an allowed band, even small energies can excite electrons in the highest filled level to the lowest unoccupied level. This mobility of electrons gives conductors their defining qualities, such as their ability to conduct electricity and heat, ability to absorb light and opacity (Encarta, 2009). Semiconductor Semiconductors are materials whose conductivity lies between conductor and insulator (Aina, 2007). These are mostly group four elements like silicon and germanium. The energy band is divided into three distinct bands. The valence band is filled with electrons; the forbidden gap between valence and conduction bands is relatively small but bigger than that of conductors. Both the forbidden gap and the conduction bands are not occupied by electrons. Some electrons have enough thermal energy for them to move from valence band to conduction band at normal temperature and become conducting electrons (Aina, 2007). Metha (2004) posited that electrical conductivity of semiconductor increase with rise in temperature. The Fermi level of semiconductor is near the top of a band but there is only a narrow forbidden energy gap above it. Semiconductor can either be insulator or conductor depending on the ability of electrons to migrate from the valence band to conduction band. Craig (1997) said silicon is a natural semiconductor that can be altered to be either an insulator or a conductor. Insulator Insulators are materials that do not allow electricity to pass through them. The energy band of insulator is divided into three bands like that of semiconductor, but the forbidden gap is very wide that no electron could move from valence band to conduction band. The conduction band will always be unoccupied by electrons, this is the reason why the material is regarded as insulator examples are diamond and quartz. The Fermi level of insulator is at the top of an allowed band and there is relatively large forbidden energy gap between this band and next higher allowed band. Because only large energies can excite the electrons, an insulator is a poor conductor of heat and electricity, cannot absorb light, and is transparent (Encarta, 2009). Importance of conductor, semiconductor and insulator Integrated circuit has taken over electronic world. The major building material of integrated circuit is silicon crystal. Silicon apart from oxygen is the most abundant element on Earth and is the principal ingredient of beach sand (Encarta). This silicon is a natural semiconductor that is useful in ceramic industries. Ceramics include the manufacture of earthenware, porcelain, bricks, and some kinds of tiles and stoneware. Silicon, a natural semiconductor is one major ingredient of ceramic, for example silicon carbide and silicon nitride are often used to make paints, such as turbine rotors used in jet engines. These ceramics are used as insulator devices to separate elements in an electrical circuit to keep the current on the desire pathway. Microprocessors, electronics circuit that functions as the central processing unit (CPU) of a computer, providing computational control. Microprocessors are also used in other advanced electronic systems, such as computer printers, automobiles, and jet airliners. The microprocessor is an integrated circuit known as microchips or chips which are complex electronic circuits consisting of extremely tiny components formed on a single, thin, flat piece of material called semiconductor. Integrated circuit has become the most pervasive technology of the 20th century. It has provided the cornerstone of modern micro-electronics and has promoted the development of the so called information society. Applications of integrated circuits range from their use in super computer- which are bringing about revolutionary advances in medical diagnosis, biotechnology, aeronautical and space engineering, telecommunications and defence systems- to the development of new consumer products capable of bringing services and information to the home and office environment that otherwise would not have been possible. In consumer electronics, integrated circuit has made possible the development of many new products, including personal calculators, computer, digital watches and video games. They have also been used to improve or lower the cost of many existing products, such as appliances, televisions, radios, and high fidelity equipment. They are used extensively in industry, traffic control, environmental monitoring and communications. Industries are springing up producing electrical cables for domestic and industrial purposes. Jobs are created in all these industries especially in ceramics and electrical cables industries. There are many small scale industries specializing in production ceramics in Nigeria. Conclusion and Recommendations Conductors, semiconductors and insulators are very important in a growing economy like ours in Nigeria. Therefore, for a sustainable human development, the place of these materials in science and technology cannot be overemphasized. They are central to science and technology especially the telecommunication sector. In view of the important position conductor, semiconductor and insulator holds in science and technology for a sustainable human development they need to be properly harness. According to Familusi (2010), these materials are present naturally both in the soil and soil surface, I therefore recommend that government, institutions and industries should make proper use of these materials for our growing economy. Government should also assist individual and institution with fund that may have interest to set up business on these materials. References Aina, J.K (2007). Basic Electronic for Colleges. Basic Concepts in Sciences. The Author. Ilorin Bernstein, G.H ” Microprocessor”. Microsoft Encarta 2009 (DVD),Redmond, WA: Corporation, 2008 “Ceramics” Microsoft Encarta 2009 (DVD) Redmond, WA: Corporation, 2008 Craig, R. B (1997). From Sand to Silicon: Manufacturing and Integrated Circuit. Scientific American, Inc. Familusi, T.O (201, May). Extent of Conductors, Semiconductors and Insulators on World Economic And Technological Growth. A Paper presented at the First International Conference of the Faculty of Science, Osun State Polytechnic, Iree. Halliday, D & Resnick, R (1978). Physics. Part 2. New York. John Wiley and Sons Metha, V.K (2004). Principle of Electronics. New Delhi, S. Chand and Company Ltd. Nelkon, M & Parker, P(1995). Advance Level Physics. Neww Delhi, CBS. Publishers and Distributors
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