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Lecture Electrical Engineering: Lecture 6 - Dr. Nasim Zafar

Upon completion of this topic on P-N Junctions, you will be able to appreciate: Knowledge of the formation of p-n junctions to explain the diode operation and to draw its I-V characteristics. so that you can draw the band diagram to explain their I-V characteristics and functionalities. Diode break down mechanisms; including the Avalanche breakdown and Zenor break down; The Zener Diodes. | Dr. Nasim Zafar Electronics 1 EEE 231 – BS Electrical Engineering Fall Semester – 2012 COMSATS Institute of Information Technology Virtual campus Islamabad Revision: 1. Semiconductor Materials: Elemental semiconductors Intrinsic and Extrinsic Semiconductor Compound semiconductors III – V Gap, GaAs II – V e.g ZnS, CdTe Mixed or Tertiary Compounds e.g. GaAsP 2. Applications: Si diodes, rectifiers, transistors and integrated circuits etc GaAs, GaP emission and absorption of light ZnS fluorescent materials Revision: 3. The Band Theory of Solids Quantum Mechanics discrete energy levels S1 – P3 – model for four valency Si – atom in the diamond lattice four nearest neighbors Sharing of four electrons S1 – P3 – level, the covalent bonding! Pauli’s Exclusion principle for overlapping S1 – P3 electron wave functions Bands 3 Revision: 4. Band Gap and Material Classification Insulators Eg: 5 – 8 eV Semiconductor Eg: 0.66 eV – 2/3 eV Metals overlapping The classification takes into account Electronic configuration Energy Band-gap Examples: Wide: Eg 5 eV (diamond) Eg ~ 8 eV (SiO2) Narrow: Eg = Si = 1.12, GaAs = 1.42 5. Charge Carriers in Semiconductors Electrons and Holes in Semiconductors Intrinsic Materials Doped – Extrinsic Materials Effective Mass Hydrogenic Model: Lecture No: 6 P-N Junction - Semiconductor Diodes Outcome: Upon completion of this topic on P-N Junctions, you will be able to appreciate: Knowledge of the formation of p-n junctions to explain the diode operation and to draw its I-V characteristics. so that you can draw the band diagram to explain their I-V characteristics and functionalities. Diode break down mechanisms; including the Avalanche breakdown and Zenor break down; The Zener Diodes. Understanding of the operation mechanism of solar cells, LEDs, lasers and FETs. Semiconductor Devices: Semiconductor devices are electronic components that use the electronic properties of . | Dr. Nasim Zafar Electronics 1 EEE 231 – BS Electrical Engineering Fall Semester – 2012 COMSATS Institute of Information Technology Virtual campus Islamabad Revision: 1. Semiconductor Materials: Elemental semiconductors Intrinsic and Extrinsic Semiconductor Compound semiconductors III – V Gap, GaAs II – V e.g ZnS, CdTe Mixed or Tertiary Compounds e.g. GaAsP 2. Applications: Si diodes, rectifiers, transistors and integrated circuits etc GaAs, GaP emission and absorption of light ZnS fluorescent materials Revision: 3. The Band Theory of Solids Quantum Mechanics discrete energy levels S1 – P3 – model for four valency Si – atom in the diamond lattice four nearest neighbors Sharing of four electrons S1 – P3 – level, the covalent bonding! Pauli’s Exclusion principle for overlapping S1 – P3 electron wave functions Bands 3 Revision: 4. Band Gap and Material Classification Insulators Eg: 5 – 8 eV Semiconductor Eg: 0.66 eV – 2/3 eV Metals .