ECE3040B_Test3_Solution - GEORGIA INSTITUTE OF TECHNOLOGY...

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ECE 3040B: Test #3, Solutions April 13, 2009 Page 1 of 7 G EORGIA I NSTITUTE OF T ECHNOLOGY S CHOOL OF E LECTRICAL AND C OMPUTER E NGINEERING ECE 3040B: Microelectronic Circuits Spring Semester 2009, Test #3 SOLUTIONS 12 Short Questions (5 points each) 1. Sketch the energy band diagram for an ideal MOS capacitor with Φ M = Φ S and an n-type semiconductor. Do you have to apply a positive or a negative potential to the gate (assume the semiconductor bulk is connected to GND) to achieve inversion at the semiconductor surface? Justify your answer. The inversion layer in an MOS capacitor with n-type semiconductor consists of holes (minority carriers). To attract holes to the semiconductor surface, a NEGATIVE potential must be applied to the gate. 2. What is known as the work function of a semiconductor? What is known as the electron affinity of a semiconductor? The work function is the energy difference between the vacuum level E 0 and the Fermi energy E F . The electron affinity is the energy difference between the vacuum level E 0 and the conduction band energy E C .
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ECE 3040B: Test #3, Solutions April 13, 2009 Page 2 of 7 3. What is known as the Fermi potential of a semiconductor? Is the Fermi potential positive or negative for a p-type semiconductor? How can you express the surface potential of the semiconductor in an MOS capacitor biased at the onset of inversion as a function of the Fermi potential? The Fermi potential of a semiconductor is the energy difference between E i and E F , divided by q, i.e. φ
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This note was uploaded on 01/17/2011 for the course ECE 3040 taught by Professor Hamblen during the Fall '07 term at Georgia Institute of Technology.

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ECE3040B_Test3_Solution - GEORGIA INSTITUTE OF TECHNOLOGY...

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