MSEASUSlides: Muddiest points: Electronic Properties II

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This slide set was used to create the MaterialsConcepts YouTube Video "Muddiest points: Electronic Properties II". Here is the link to that video: https://www.youtube.com/watch?v=-MC_YX7ruhs To study the vocab used in this video, visit this site: http://quizlet.com/24383455/72-electronic-properties-ii-intrinsic-extrinsic-semiconductors-flash-cards/ This work was supported by NSF Grants #0836041 and #1226325

Text of MSEASUSlides: Muddiest points: Electronic Properties II

  • 1. Muddiest Points Electronic Properties II: Intrinsic & Extrinsic Semiconductors Muddiest Points: What are the differences between intrinsic and extrinsic semiconductors? What are the differences between n type and p type extrinsic semiconductors? How does temperature affect each type of semiconductor? What are the differences in the conductivity equation for intrinsic and extrinsic semiconductors? What is the relation of electron and electron-hole mobility to conductivity?
  • 2. Intrinsic Semiconductors ENERGY No Dopants Less than 1021/m3 impurity atoms (10-6 wt% impurities) electron-hole pairs (n=p=ni) Conductivity increases with an increase in temperature (creates more e-h pairs) Energy Gap (Eg) is constant and between 0.1eV-2eV Group IV elemental semiconductors Group III + Group V are compound semiconductors
  • 3. Extrinsic Semiconductors: p-type ENERGY p-type Dopants Impurity atoms have one less valence electron than the host Majority Charge Carriers: electron holes (p>>n) Minority Charge Carriers: electrons (n>p) Minority Charge Carriers: electron holes (p>n) = + = conductivity (ohm-m)-1 p = positive carrier density (# of carriers/m3) q = electric charge 1.6x10-19 (C) h = electron hole mobility (m2/(V-s))
  • 13. Example 1: p-type Conductivity What is the conductivity of silicon containing 3.13 x 1021 boron dopant atoms per m3? Silicon has an electron mobility of 0.14 (m2/(V-s)) and a hole mobility of 0.05 (m2/(V-s)). = + = 0.05 (m2/(V-s)) = (3.13 x 1021 = 3.13 x 1021 m-3 m-3)(1.6x10-19 C)(0.05 m2/(V-s)) = . (-m)-1
  • 14. Conductivity Equation: n-type Extrinsic Semiconductors: n-type (n>>p) = + = conductivity (ohm-m)-1 n = negative carrier density (# of carriers/m3) q = electric charge 1.6x10-19 (C) e = electron mobility (m2/(V-s))
  • 15. Example 2: n-type Conductivity What is the conductivity of silicon containing 3.13 x 1021 phosphorus dopant atoms per m3? Silicon has an electron mobility of 0.14 (m2/(Vs)) and a hole mobility of 0.05 (m2/(V-s)). = + = 0.14 (m2/(V-s)) = (3.13 x 1021 = 3.13 x 1021 m-3 m-3)(1.6x10-19 C)(0.14 m2/(V-s)) = . (-m)-1
  • 16. Wrap-Up Electronic Properties II: Intrinsic & Extrinsic Semiconductors What are the differences between intrinsic and extrinsic semiconductors? What are the differences between n type and p type extrinsic semiconductors? How does temperature affect each type of semiconductor? What are the differences in the conductivity equation for intrinsic and extrinsic semiconductors? What is the relation of electron and electronhole mobility to conductivity?