lecture28

# lecture28 - Lecture 28 Monday April 11 EE 332 Semiconductor...

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Unformatted text preview: Lecture 28 Monday April 11 EE 332 Semiconductor Devices Problem Assignment Monday Æ Problems S3.4a Definitions φ f = separation of E i and E F φ s is total bend in the band at the oxide interface. φ s >0 Æ bend down, φ s = 0 Æ flat band. When φ s > φ f inversion exists. = = i A f s n N q kT ln 2 2 ) inv ( φ φ fs i f E E q − = φ For strong inversion Interface Charge Produces Band Bending. Define Flat Band Potential = V FB = Φ m- Φ s -Q i /C’ ox = Φ ms-Q i /C’ ox Interface Charge Sodium ions are common contaminants in SiO 2 and they are relatively mobile. 1. Let positive mobile Na + be Q m (problem solved) 2. Trapped charge in oxide = Q ot (problem solved) 3. Charge at interface states due to the termination of the Si crystal lattice be Q it 4. At Si-SiO 2 interface, let charges in SiO x be Q f Q it +Q f =10 10 /cm 2 on {100} surface and a factor of ten higher on {111} surface. Q ot and Q m are near zero for a good process. Let Q i =Q f +Q it =total interface charge In the Depletion Region () () [ ] w C...
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lecture28 - Lecture 28 Monday April 11 EE 332 Semiconductor...

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