1
GATE ECE 2003
MCQ (Single Correct Answer)
+2
-0.6
The electron concentration in a sample of uniformly doped n-type silicon at 300oK varies linearly from $$10^{17}/cm^3$$ at x = 0 to $$6\times10^{16}/cm^3$$ at x = 2 $$\mu m$$. Assume a situation that electrons are supplied to keep this concentration gradient constant with time.If electronic charge is $$1.6\times10^{-19}\;coulomb$$ and the diffusion constant $$D_n=3\;cm^2/s$$, the current density in the silicon, if no electric field is present is
A
Zero
B
120 A/cm2
C
+1120 A/cm2
D
-1120 A/cm2
2
GATE ECE 2003
MCQ (Single Correct Answer)
+2
-0.6
Choose proper substitutes for X and Y to make the following statement correct Tunnel diode and Avalanche photodiode are operated in X bias and Y bias respectively.
A
X: reverse, Y: reverse
B
X: reverse, Y: forward
C
X: forward, Y: reverse
D
X: forward, Y: forward
3
GATE ECE 2003
MCQ (Single Correct Answer)
+2
-0.6
If P is Passivation, Q is n-well implant, R is metallization and S is source/drain diffusion, then the order in which they are carried out in a standard n-well CMOS fabrication process, is
A
P-Q-R-S
B
Q-S-R-P
C
R-P-S-Q
D
S-R-Q-P
4
GATE ECE 2003
MCQ (Single Correct Answer)
+2
-0.6
For an n-channel enhancement type MOSFET, if the source is connected at a higher potential than that of the bulk (i.e. VSB > 0), the threshold voltage VT of the MOSFET will
A
remain unchanged
B
decrease
C
change polarity
D
increase
EXAM MAP