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ESE 2021 Technical Quiz | 32 Semiconductors-1
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Question 1
The resistivity of a uniformly doped n-type silicon sample is 0.5 Ω-cm. If the electron mobility (μn) is 1250 cm2/V-sec and the charge of an electron is 1.6 × 10–19 Coulomb, the donor impurity concentration (ND) in the sample is
Question 2
Which of the following semi-conductor parameters vary with temperature?
i) Intrinsic concentration (ηi)
ii) Mobility (μ)
iii) Conductivity (σ)
iv) Energy gap (EG)
i) Intrinsic concentration (ηi)
ii) Mobility (μ)
iii) Conductivity (σ)
iv) Energy gap (EG)
Question 3
An intrinsic semiconductor bar of Si is doped with donor type impurity to the extent of 1 atom per 108 silicon atoms, then the resistivity of silicon crystal will be
(atomic density of Si crystals = 5 x 1022 atoms/cm3 and μn = 1300 cm2N-sec)
(atomic density of Si crystals = 5 x 1022 atoms/cm3 and μn = 1300 cm2N-sec)
Question 4
Assume electronic charge 
and electron mobility 
If the concentration gradient of electrons injected into a P-type silicon sample is 
the magnitude of electron diffusion current density (in A/cm2) is _________.
and electron mobility If the concentration gradient of electrons injected into a P-type silicon sample is the magnitude of electron diffusion current density (in A/cm2) is _________. Question 5
A semiconductor having electron mobility
, hole mobility
, intrinsic carrier concentration as 
is kept at 300 ° K. The maximum value of resistivity is _________ Ω-m.
, hole mobility, intrinsic carrier concentration as is kept at 300 ° K. The maximum value of resistivity is _________ Ω-m.- 166 attempts
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