1
GATE ECE 2010
+2
-0.6
The silicon sample with unit cross-sectional area shown below is in thermal equilibrium. The following information is given: T=300K, electronic charge=1.6x10- 19C, thermal voltage=26mV and electron mobility = 1350cm2/V-s

The magnitude of the electron drift current density at x=0.5 μm is

A
2.16x104 A/cm2
B
1.08x104 A/cm2
C
4.32x103 A/cm2
D
6.48x102 A/cm2
2
GATE ECE 2005
+2
-0.6
A silicon sample 'A' is doped with 1018 atoms/cm3 of Boron. Another sample 'B' of identical dimensions is doped with 1018 atoms/cm3 of Phosphorus. The ratio of electron to hole mobility is 1/3. The ratio of conductivity of the sample A to B is
A
3
B
1/3
C
2/3
D
3/2
3
GATE ECE 2003
+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
+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
$$10^{-4}\;\Omega$$
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