1
GATE ECE 2003
MCQ (Single Correct Answer)
+2
-0.6
At 300 K, for a diode current of 1 mA, a certain germanium diode requires a forward bias of 0.1435 V. Where as a certain silicon diode requires a forward bias of 0.718 V. Under the conditions stated above, the closest approximation of the ratio of reverse saturation current in germanium diode to that in silicon diode is
A
1
B
5
C
4 × 103
D
8 × 103
2
GATE ECE 2003
MCQ (Single Correct Answer)
+2
-0.6
An n-type silicon bar 0.1 cm long and $$100\;\mu m^2$$ in cross-sectional area has a majority carrier concentration of $$5\times10^{20}/m^3$$ and the carrier mobility is $$0.13\;\;m^2/v-s\;$$ at 300oK. if the charge of an electron is 1.6×10-19 coulomb, then the resistance of the bar is
A
$$10^6\;\Omega$$
B
$$10^4\;\Omega$$
C
$$10^{-1}\;\Omega$$
D
$$10^{-4}\;\Omega$$
3
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
4
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
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