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Department of Electronics Semiconductor Devices 27 Atsufumi Hirohata 11:00 Thursday, 4/December/2014 (P/T 005)

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Exercise 6 Calculate the depletion layer capacity at a reverse bias V R = 0.5 V in a Au/n-Si Schottky diode. Assume the following parameters: Au work function: M = 4.80 eV n-region: doping density of N D = 1 10 21 m -3 Si electron affinity: = 4.05 eV Si Fermi level: E F = E C 0.15 eV permittivity: = 0 = 12.0 8.854 10 -12 F/m and q = 1.6 10 -19 C. q(V bi + V R ) Depletion layer EFEF qV R ECEC EVEV

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Answer to Exercise 6 The built-in potential can be calculated as For an n-type contact, : Ohmic contact : Schottky contact with the barrier height of Hence, By substituting the given parameters, Depletion layer capacity C is

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27 Metal Oxide Semiconductor Junction Bias application Surface space-charge MOS FET

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Realistic Schottky Barrier Image force and Shottky barrier : * S. M. Sze, Physics of Semiconductor Devices (Wiley, New York, 2006).

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Metal Oxide Semiconductor Junction n-type semiconductor at V = 0 : * S. M. Sze, Physics of Semiconductor Devices (Wiley, New York, 2006). p-type semiconductor at V = 0 :

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Metal Oxide Semiconductor (MOS) p-type Si / SiO 2 / poly-Si : * http://www.wikipedia.org/ In 2007, Intel introduced p-type Si / high-k oxides (HfO 2 etc.) / metal.

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Bias Applications Reverse bias (accumulation) : * S. M. Sze, Physics of Semiconductor Devices (Wiley, New York, 2006). Forward bias (depletion) : Forward bias (inversion) :

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Surface Space-Charge p-type semiconductor : * S. M. Sze, Physics of Semiconductor Devices (Wiley, New York, 2006).

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Space-Charge Variation With different surface potentials S : * S. M. Sze, Physics of Semiconductor Devices (Wiley, New York, 2006).

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Charge Distributions Band diagram of a metal oxide semiconductor junction under an inversion condition : * S. M. Sze, Physics of Semiconductor Devices (Wiley, New York, 2006). Charge distributions : Electric field distributions : Potential distributions :

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MOS Field Effect Transistor (FET) One of the most popular transistors for amplification and switching : * http://www.wikipedia.org/

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MOS FET Operation Current-Voltage characteristics : * http://www.wikipedia.org/

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MOS FET Operation Gate functionality : * https://www.youtube.com/watch?v=DquJSQasWG0