ECE 440 Homework XV Spring 2006 Due: Wednesday, April 19, 2006 1. Aluminum and polysilicon are commonly used as gate metals for the MOS structure in silicon. Assume that platinum is used as the gate metal. Reconstruct a diagram similar to Figure 6-17 showing the variation of the metal-semiconductor work function potential difference Φ ms with substrate doping concentration. The work function of Pt is 5.7 V and the electron affinity of silicon is 4.0 V. Show your work and draw to scale with accuracy. 2. (a) Find the voltage V FB required to reduce to zero the negative charge induced at the semiconductor surface by a sheet of positive charge Q ox located x’ below the metal. (b) In the case of an arbitrary distribution of charge
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