2_diode_slide_achar

2_diode_slide_achar - 2 March 2009; R. Achar, ELEC 2507,...

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Unformatted text preview: 2 March 2009; R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University 1 ELEC 2507 Analog Electronics 1 2 March 2009; R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University 2 ELEC 2507 Diodes 2 March 2009; R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University 3 Diodes Most fundamental Analog Device Two terminal device Acts like a switch (Allows current in one direction and blocks in the other direction) Symbol: Applications: Rectifiers, Voltage Regulators, Filters, Logic Switches ANODE D1 DIODE CATHODE 2 March 2009; R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University 4 Diodes Diodes are made from a large variety of materials including silicon, germanium, gallium arsenide, silicon carbide ANODE D1 DIODE CATHODE 2 March 2009; R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University 5 Semiconductor Physics Materials can be classified into three categories based on their electrical properties: Conductors offer very low resistance for current flow (e.g. aluminum, copper, iron). Insulators offer very high resistance for current flow (e.g. Fibreglass, wood, plastics, cotton). Semiconductors offer medium resistance for current flow (e.g. silicon, germanium). Their conductivity (and thus resistivity) can be varied significantly based on external parameters such as temperature, impurities, etc . This makes them highly attractive for deployment in electronic devices. 2 March 2009; R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University 6 Charge carrier types in semiconductors Two types: Free electrons : Electrons that are not confined to their atoms in chemical bonds are able to move in the lattice. These electrons act as negative charge carriers. Free holes : A hole is defined as a lack of an electron, which acts as a positive charge with respect to the sea of electrons surrounding it; since free electrons move in the lattice, the holes (i.e., the positions where electrons lack) also move. Therefore holes can be viewed as positive charge carriers. 2 March 2009; R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University R. Achar, ELEC 2507, Carleton University 7 Types of charge carriers & currents in semiconductors Charge Carriers: Electrons (-ve charge) Holes (+ve charge barb4right...
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2_diode_slide_achar - 2 March 2009; R. Achar, ELEC 2507,...

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