ELCT363_Lecture12_Carrier_ConcentrationII

ELCT363_Lecture12_Carrier_ConcentrationII - ELCT 363:...

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Unformatted text preview: ELCT 363: Intro. to Microelectronics Lecture 12; Slide Mandal/Fall 2011 Announcement Homework #2 is posted in the Assignment section of the Blackboard. Due date is : October 4, 2011 1 ELCT 363: Intro. to Microelectronics Lecture 12; Slide Mandal/Fall 2011 Doped Semiconductors “Donor” dopants n-type semiconductor the most of the mobile charges are free electrons “ could donate free electrons ” “Acceptor” dopants p-type semiconductor most of the mobile charges are holes “holes could accept free electrons ” At 300K, free electron concentration in Si, n 300K = 1.3 × 10 10 cm-3 Resistance of Si at 300K = 4.8 × 10 5 Ohm Pure Si is not a good conductor of electricity. 2 Doping of semiconductor is to decrease its resisitance: What is the Resistance of doped Silicon at 300K? ELCT 363: Intro. to Microelectronics Lecture 12; Slide Mandal/Fall 2011 Example : Consider a (1 cm×1cm× 1cm) Si sample doped with donor concentration of 2×10 16 cm-3 ? What would be the resistance of the doped silicon? ( μ n = 1000 cm 2 .V-1 .s-1 ) Resistance of Donor-Doped Silicon Sample n = N D = 2×10 16 cm-3 μ n = 1000 cm 2 /(V ×s) q = 1.6 ×10-19 C σ = 1.6 ×10-19 C × 2×10 16 cm-3 × 1000 cm 2 .V-1 .s-1 = 3.2 Ohm-1 .cm-1 A L qn R × = μ 1 Therefore, The resistance of a doped Si crystal can be significantly lower than that of intrinsic Si (R...
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This note was uploaded on 10/25/2011 for the course ELCT 363 taught by Professor Mandal during the Spring '11 term at South Carolina.

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ELCT363_Lecture12_Carrier_ConcentrationII - ELCT 363:...

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