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GATE EC : Electronic Devices & Circuits Champion Quiz 3
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Question 1
A silicon sample is uniformly doped with donor type impurities with a concentration of 1016 /cm3. The electron and hole mobilities in the sample are 1200 cm2/V-s and 400 cm2 /V-s respectively.
Assume complete ionization of impurities. The charge of an electron is 1.6 × 10–19 C. The resistivity of the sample (in Ω-cm) is _________.
Assume complete ionization of impurities. The charge of an electron is 1.6 × 10–19 C. The resistivity of the sample (in Ω-cm) is _________.
Question 2
The intrinsic carrier concentration of silicon sample of 300 K is 
If after doping, the number of majority carriers is 
the minority carrier concentration is
If after doping, the number of majority carriers is the minority carrier concentration is Question 3
The bandgap of silicon at 300 K is
Question 4
A continuity equation is also called as the law of conservation of
Question 5
The electron and hole concentrations, n and p respectively obey the relation 
where ni is the intrinsic carrier density. This expression is valid for which of the following?
where ni is the intrinsic carrier density. This expression is valid for which of the following? Question 6
A piece of silicon is doped uniformly with phosphorous with a doping concentration 1016 /cm3. The expected value of mobility versus doping concentration for silicon assuming full dopant ionization is shown below. The charge of an electron is 
C. The conductivity (in S cm–1) of the silicon sample at 300 K is____
Hole and Electron Mobility in Silicon at 300 K
Doping concentration (cm–3)
C. The conductivity (in S cm–1) of the silicon sample at 300 K is____ Hole and Electron Mobility in Silicon at 300 K
Doping concentration (cm–3)
Question 7
In the circuit shown below, the silicon npn transistor Q has a very high value of β. The required value of R2 in k Ω to produce IC = 1 mA is
Question 8
Two sequences x1 [n] and x2 [n] have the same energy. Suppose x1[n] = a 0.5n u[n], where a is a positive real number and u[n] is the unit step sequence. Assume
Then the value of a is__________.
Then the value of a is__________.
Question 9
A heavily doped n − type semiconductor has the following data:
Hole-electron mobility ratio: 0.4
Doping concentration : 4.2 × 108 atoms/m3
Intrinsic concentration : 1.5 × 104 atoms/m3
The ratio of conductance of the n − type semiconductor to that of the intrinsic semiconductor of same material and at the same temperature is given by
Question 10
The electron and hole concentrations in an intrinsic semiconductor are ni per cm3 at 300 K. Now, if acceptor impurities are introduced with a concentration of NA per cm3 (where NA>>ni), the electron concentration per cm3 at 300 K will be:
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Mar 13ESE & GATE EC
