Electronic Devices and VLSI
PN Junction
Marks 1Marks 2
Semiconductor Physics
Marks 1Marks 2
IC Basics and MOSFET
Marks 1Marks 2
BJT and FET
Marks 1Marks 2
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 1992
MCQ (Single Correct Answer)
+2
-0.6
A semiconductor is irradiated with light such that carriers are uniformly generated throughout its volume. The semiconductor is n-type with $$N_D=10^{19}/cm^3$$. If the excess electron concentration in the steady state id $$\triangle n=10^{15}/cm^3$$ and if $$\tau_p=10\;\mu\;sec$$ [minority carrier life time] the generation rate due to irradiation
A
$$is\;10^{20}\;e-h\;pairs/cm^3/sec$$
B
$$is\;10^{24}\;e-h\;pairs/cm^3/sec$$
C
$$is\;10^{10}\;e-h\;pairs/cm^3/sec$$
D
cannot be determined as the given data is insufficient
3
GATE ECE 1991
MCQ (Single Correct Answer)
+2
-0.6
A silicon sample is uniformly doped with 1016 phosphorous atoms/cm3 and 2 ×1016 boron atoms/cm3. If all the dopants are fully ionized, the material is
A
n-type with carrier concentration of 1016/cm3
B
p-type with carrier concentration of 1016/cm3
C
p-type with carrier concentration of 2 ×1016/cm3
D
n-type with carrier concentration of 2 ×1016/cm3
4
GATE ECE 1987
MCQ (More than One Correct Answer)
+2
-0
In an intrinsic semiconductor the free electron concentration depends on
A
Effective mass of electrons only.
B
Effective mass of holes only.
C
Temperature of the Semiconductor.
D
Width of the forbidden energy band of the semiconductor.
GATE ECE Subjects
Signals and Systems
Network Theory
Control Systems
Digital Circuits
General Aptitude
Electronic Devices and VLSI
Analog Circuits
Engineering Mathematics
Microprocessors
Communications
Electromagnetics