Electronic Circuits

• A material that has conductivity but less than a conductor

  Semiconductor
• The reciprocal of conductivity

  Resistivity
• The unit of resistivity

  ohm-meter
• The resistivity of a semiconductor is greater


  than the resistivity of a conductor but less than the resistivity of an insulator
• Illustrates how much energy is required to move an electron from valence band going through the forbidden band gap onto the conduction band

  Energy band diagram
• Pure semiconductors

  Intrinsic semiconductors
• silicon and germanium has

  negative temperature coefficient
• impurity atoms are added

  Extrinsic semiconductor
• Impurity atoms that belong in group 5 of the periodic table


  Pentavalent
• Impurity atoms that belong in group 3 of the periodic table

  Trivalent
• Process of adding impurity atoms to pure semiconductors

  doping
• We add pentavalent impurity to

  N-type
• We add trivalent impurity to

  P-type
• N-type becomes

  donor type
• P-type becomes

  acceptor types
• The charge carrier for n type is

  electron
• The charge carrier of p type is

  hole
• absence of e

  hole
• Under thermal equilibrium to product of free electron concentration and the free hole concentration is equal to the square of intrinsic carrire concentration

  Mass action law
• total positive charge=total negative charge is needed to achieve

  electrical neutrality
• Metals are (unipolar/bipolar)

  unipolar
• Semiconductors are (unipolar/bipolar)

  bipolar