1. A solid cylindrical piece of silicon has radius 2mm and length 1cm. Calculate the resistance along the length of the silicon assuming:-

(a) a donor concentration of 5x1022m-3

(b) an acceptor concentration of 5x1022m-3

(c) the silicon is intrinsic.

[Assume ni=1.2x1016m-3, e=0.14m2V-1s-1, h=0.048m2V-1s-1, e=1.6x10-19C].

2. Calculate the equilibrium concentrations of electrons and holes in silicon at 290K with

(a) donor concentration Nd=1.5x1022m-3,

(b) acceptor concentration,Na=5x1020m-3 and

(c) Nd=7.5x1016m-3 and Na=5x1016m-3.

[Assume ni=1.2x1016m-3].

3. Calculate the acceptor dopant density which is needed to fabricate a resistor of value 870 in an integrated circuit. The resistors length and breadth are 50m and 5m respectively and the depth of diffusion can be assumed to be 2.5m. [Hole mobility p=0.048m2V-1s-1].

(a) a donor concentration of 5x1022m-3

(b) an acceptor concentration of 5x1022m-3

(c) the silicon is intrinsic.

[Assume ni=1.2x1016m-3, e=0.14m2V-1s-1, h=0.048m2V-1s-1, e=1.6x10-19C].

2. Calculate the equilibrium concentrations of electrons and holes in silicon at 290K with

(a) donor concentration Nd=1.5x1022m-3,

(b) acceptor concentration,Na=5x1020m-3 and

(c) Nd=7.5x1016m-3 and Na=5x1016m-3.

[Assume ni=1.2x1016m-3].

3. Calculate the acceptor dopant density which is needed to fabricate a resistor of value 870 in an integrated circuit. The resistors length and breadth are 50m and 5m respectively and the depth of diffusion can be assumed to be 2.5m. [Hole mobility p=0.048m2V-1s-1].

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