Lecture 4

ETE411 :: Semiconductor
ATOMIC BONDING
   Ionic bond
   Covalent bond
   Metallic bond
   Van der Waals bond
Ionic bond
An ionic bond is a type of chemical bond that involves a metal
and a non-metal ion through electrostatic attra...
Covalent bond
   Covalent chemical bonds
    involve the sharing of a
    pair of valence electrons
    by two atoms, in ...
Metallic bond
    In the metallic bond, an atom achieves a
    more stable configuration by sharing the
    electrons in ...
Van der Waals bond
   These forces occur between the molecules of nonpolar
    covalent substances such as H , Cl , and H...
Imperfections in Solids
Summery of chapter 1
Ete411 Lec4
Ete411 Lec4
Ete411 Lec4
Ete411 Lec4
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Ete411 Lec4

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Lecture on Introduction of Semiconductor at North South University as the undergraduate course (ETE411)
=======================
Dr. Mashiur Rahman
Assistant Professor
Dept. of Electrical Engineering and Computer Science
North South University, Dhaka, Bangladesh
http://mashiur.biggani.org

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Ete411 Lec4

  1. 1. Lecture 4 ETE411 :: Semiconductor
  2. 2. ATOMIC BONDING  Ionic bond  Covalent bond  Metallic bond  Van der Waals bond
  3. 3. Ionic bond An ionic bond is a type of chemical bond that involves a metal and a non-metal ion through electrostatic attraction. It is a bond formed by the attraction between two oppositely charged ions. The metal donates one or more electrons, forming a positively charged ion or cation with a stable electron configuration. These electrons then enter the non metal, causing it to form a negatively charged ion or anion which also has a stable electron configuration. The electrostatic attraction between the oppositely charged ions causes them to come together and form a bond.
  4. 4. Covalent bond  Covalent chemical bonds involve the sharing of a pair of valence electrons by two atoms, in contrast to the transfer of electrons in ionic bonds. Such bonds lead to stable molecules if they share electrons in such a way as to create a noble gas configuration for each atom.
  5. 5. Metallic bond  In the metallic bond, an atom achieves a more stable configuration by sharing the electrons in its outer shell with many other atoms. Metallic bonds prevail in elements in which the valence electrons are not tightly bound with the nucleus, namely metals, thus the name metallic bonding. In this type of bond, each atom in a metal crystal contributes all the electrons in its valence shell to all other atoms in the crystal
  6. 6. Van der Waals bond  These forces occur between the molecules of nonpolar covalent substances such as H , Cl , and He. These forces are generally believed to be caused by a temporary dipole, or unequal charge distribution, as electrons constantly move about in an atom, ion, or molecule.  At a given instant, more electrons may be in one region than in another region, as illustrated in Figure. The temporary dipole induces a similar temporary dipole on a nearby atom, ion, or molecule. Every instant, billions of these temporary dipoles form, break apart, and reform to act as a weak electrostatic force of attraction known as van der Waals forces.
  7. 7. Imperfections in Solids
  8. 8. Summery of chapter 1

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