Discussion :: Exam Questions Paper
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A MOSFET has a threshold voltage of 1 V and oxide thickness of 500 x 10-8 [εr = 3.9; ε0 = 8.85 x 10-14 F/cm, q = 1.6 x 10-19 c]. The region under the gate is ion implanted for threshold voltage tailoring. The base and type of impant required to shift threshold voltage to - 1 V are __________ .
A.
8.6 x 1011/cm2, p-type
|
B.
8.6 x 1011/cm2, n-type
|
C.
0.86 x 109/cm2, p-type
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D.
1.02 x 1012/cm2, n-type
|
Answer : Option A
Explanation :
VT(new) = VT(odd) +
= 6.903 x 10-8
∴
∴
fB = - 8.6 x 1011
The threshold voltage is always negative for p-channel and hence implant is of p-type.
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