Silicon (Si) is the best-known semiconductor. Boron, germanium zinc sulfide, Mercury selenide are some the few of hundreds of semiconductors. Semiconductors also could be found in nature like zinc selenide (ZnS), cuprite (CU2O) and galend (PbS). Semiconductors are classified in numerous ways. They exist as pure elements such as Si, B and compounds such as gallium arsenide. Semiconductors could also be categorized as Elemental, Binary and Ternary. • Elemental Semiconductors: These are single elemental semiconductors belong to B subgroups III, IV, V and VI groups of the periodic table. Carbon (diamond) Silicon, Boron, Gray tin, Phosphorous, Germanium, Selenium, and Tellurium are some of the elemental semiconductors. • Compound Semiconductors: They have a chemical composition of two or more elements mainly from group III and V o Binary Compound: As the name depicts binary compounds are made up of two elements. For example SiC, GaAs and CdS. Binary semiconductors could be further divided as IV-VI, III-V, II-VI and I-VII semiconductors. o Ternary Compounds: AlGaAs, CdHgTe are some of the ternary compounds that consist of three elements. It is also necessary to understand the meaning of Intrinsic and Extrinsic. Intrinsic materials have a pure chemical composition without any impurities and thus have less electrical conductivity. For example a pure Si acts as an insulators as there are no free electrons in pure Si structure. Extrinsic crystals are formed when small amounts of impurities are added to intrinsic crystal structure, thus extrinsic crystals have better electrical conductivity than intrinsic crystals. The process of introduction of impurities to intrinsic crystalline structure is known as doping and will be explained below.... ... middle of paper ... ...l voltage could alter the height of the potential barrier. When positive terminal of a battery is connected to n-type and the negative terminal of the battery is connected to the p-type the electrons in the n-type will be attracted to the positive terminal while holes in p-type will be attracted to the negative terminal. Thus the depletion layer will increase preventing a current flow across the p-n junctions. This is called reversed bias. A current flow is only generated when the positive terminal of the battery is connected to the p-type and the negative terminal of the battery is connected to the p-type. The negative terminal will repel the electrons in the n-type while the positive terminal will repel the holes in p-type and as a result the depletion layer will be reduced and this is called forward bias. Thus diodes will only function when it is in forward bias.
Ionic compounds are normally a combination of a metal, along with one or more non-metals. If you recognize the two ions, you have the name of the compound. For example, the familiar calcium ion, Ca2+ must combine with two iodides, I–, to afford calcium iodide, CaI2. For ionic compounds this means that the formula unit must have an equal number of positive and negative charges because ionic
Metals contain a sea of electrons (which are negatively charged) and which flow throughout the metal. This is what allows electric current to flow so well in all metals. An electrode is a component of an electric circuit that connects the wiring of the circuit to a gas or electrolyte. A compound that conducts in a solution is called an electrolyte. The electrically positive electrode is called the anode and the negative electrode the cathode.
The symbol “As” from the periodic table, belongs to the chemical element Arsenic. Its located in group 15, period 4, and is clasificat as semi-metals. Arsenic’s atomic number is 33, and has a density of 5.776 grams per cubic centimeter. Arsenic melting point is 1090 K (817°C or 1503°F) and the boiling point is 887 K (614°C or 1137°F). The element specific gravities are 1.97 and 5.73, they are respectively to his two solid modifications: yellow, and grey (or metallic). Arsenic’s appearance is steel grey, very brittle, crystalline, and is classified as a semi-metal since it has properties of both.
Sulfur goes back to the ancient times but it was called brimstone. In 1979, a French chemist named Antoine Lavoisier recognized sulfur was an element and added it to his list of elements. The element sulfur is considered a nonmetal and is the 10th most abundant element in the universe. On the periodic table sulfur is in group sixteen and it is a representative element. Sulfur has an atomic mass of 32.07 with an atomic number of 16. There are three energy levels for sulfur the first energy level is two, the second energy level is eight, and the third energy level is six.
The empirical formula of a compound shows the simplest ratio in which atoms of constituent elements of the compound are present in 1 molecule of the compound.
2 Elements are substances that cannot be broken down further into simpler substances by chemical means. There are currently 103 known elements from which all matter that exists is made. And they each have their own atomic number based ...
The oxide of aluminum is amphoteric—showing both acidic and basic properties. The most important compounds include the oxide, hydroxide, sulfate, and mixed sulfate compounds. Anhydrous aluminum chloride is important in the oil and synthetic-chemical industries. Many gemstones—ruby and sapphire, for example—consist mainly of crystalline aluminum oxide.
A chemical element present only in minute amounts in a particular sample or environment is called trace element. Residual elements are also known as trace elements.
characteristics. Degree of metallic character is related to an element’s ability to lose electrons while degree of nonmetallic character is related to an element’s ability to gain electrons. The final periodic trend, ionization energy, the energy required to remove an electron from an atom, generally increases when moving across the table from left to right and decreases when moving down the table. Because their valence shells are full, noble gases have very high ionization energies with the greatest ionization energy belonging to Helium.
The Periodic Table of Elements is commonly used today when studying elements. This table’s history begins in ancient times when Greek scientists first started discovering different elements. Over the years, many different forms of the periodic table have been made which set the basis for the modern table we use today. This table includes over 100 elements and are arranged by groups and periods. Groups being vertical columns and periods being horizontal columns. With all of the research conducted over the years and the organization of this table, it is easy to use when needed.
Pure silicon nitride is difficult to produce as a fully dense material. This covalently bonded material does not readily sinter and cannot be heated over 1850oC as it dissociates into silicon and nitrogen at these
Semiconductors are the crossbreed of the other two types. Semiconductors are usually a conducting material that has been "doped" or has been added to from an insulating material. This makes it so the charges don't want to move freely, but they can still move. Now, just like lightning, charges have a tendency to try to make their way to the earth if they can. This is why if you have a conducting material and connect it to the earth with a wire or something, it is said to be grounded.
Grundmann, Marius. Physics of Semiconductors: An Introduction Including Devices and Nanophysics. New York: Springer, 2006. Print.
Engineer dates back to 1325 when an engine’er, someone who operates an engine, was referred to by a conductor as an engineer. (Ford)
Electroless nickel (EN) plating was discovered by Brenner & Riddell in 1946. (1) EN plating is being large economically accessible under 30 years, is generally youthful compared with other plating. However, it has obtained significant industrial importance, being the most vital catalytic process in use today with a development rate of 5% annually. (2)