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Marathon Series EDC

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Question 1

Fermi energy level for p-type semiconductor lies

Question 2

At what condition does the Fermi energy level (EF) lie exactly between the band gap for intrinsic semiconductor?

Question 3

Considers a silicon semiconductor at T = 300 K in which acceptor concentration Na = 1016 cm–3 and donor concentration Nd = 3 × 1015 cm–3. Then the type of the compensated semiconductor and the minority carrier concentration are?

(Assume complete impurity ionization and intrinsic carrier concentration ni = 1.5 × 1010 cm–3)

Question 4

For an npn BJT transistor, how does the common-emitter current gain β depend on the relative dopings of the base region and the emitter region, NA/ND and the width of base W?

Question 5

An idea MOS diode is fabricated on a p-type silicon substrate having a doping concentration of NA = 1016 cm-3. What is the work-function ϕs (eV) of the silicon substrate at room temperature?

(for silicon, Eg = 1.1eV, ϕx = 4.05 eV), ni = 1.5 × 1010 cm-3 at 300 K, VT = 26 mV)

Question 6

A MOS capacitor has an oxide layer thickness of 300 Å and flat band voltage of –1.3 V, the effective positive charge at the semiconductor oxide layer interface Qs = 5.5 × C/cmThe metal semiconductor work function potential difference Φms is __________ mV. (Assume and F/cm.

Question 7

If a material is having a bandgap of 1.73 eV, then the wavelength of photons emitted from it will be ______________ x cm.

Question 8Multiple Correct Options

A PN junction ‘1’ with has reverse breakdown voltage and depletion capacitance. Another PN junction ‘2’ with has reverse breakdown voltage and depletion capacitance. Which among the following is true?

Question 9

At reverse saturation current of a germanium diode is. If it is forward biased by, then the current in amperes through the diode is____

Question 10Multiple Correct Options

In a tunnel diode, which of the following is/are true.

Question 11

A photo diode has a quantum efficiency of when photons of energy are incident upon it. Then the incident optical power in μW required to obtain a photocurrent of is____

Question 12

What is the ratio of Minimum Conductivity to Intrinsic Conductivity of a material when the Mobility of electron is two times the mobility of hole.

Question 13

An ideal n–channel MOSFET has the following parameters : mobility of electrons = 500 cm2 /V–sec, threshold voltage VTN = 0.6V and oxide thickness tox = 200Å. The MOSFET is biased in the saturation region at VGS = 5 V to get the saturation drain current (ID (sat)) of 6 mA, the required aspect ratio is _______________.

(Assume that the permittivity of oxide layer is 34.5 × 10–14 F/ cm)

Question 14

Find the ratio of Transconductance of MOSFET when it is operating in sub threshold region to the Saturation Region

Question 15

Consider a silicon PN junction at T = 300 k with acceptor concentration of Na = 1018 cm–3 and donor concentration of Nd = 1015 cm–3. If we change the acceptor doping concentration to Na = 1016 cm–3 by keeping all other parameters constant, then the percentage decrease in built – in potential of the junction will be equal to ________ %.

(Assume ni = 1.5 × 1010 cm–3, kT = 0.026 eV)

Question 16

An npn BJT having uniform doping ofis operating in inverse active region with, shown below. The minority carrier concentration at x=is _______

()

Question 17

For an n–channel E – MOSFET used in the circuit shown below, the threshold voltage, VT = 1V, the channel length modulation parameter   = 0 and = 0.3 mA/V2. Then the output voltage Vo is

Question 18

A depletion type N-channel MOSFET is biased in linear region for use as a voltage controlled resistor. At VGS = 4 V, the drain to source resistance (rds) found to be 1KΩ, if VGS is increased to 6 V, then the value of rds is _________ KΩ. (Assume, Threshold voltage, VTh = –1 V, the value of VDS to be very small )

Question 19

Consider a P- MOS capacitor. Let Nd = 1015cm–3ms= –0.272 V, tox = 500 Å and Q’ss =1010cm–2. What will be the flat-band voltage_________ (in mill volt)?(integer value

Question 20

Consider a MOS structure with P-type silicon. The metal-semiconductor work function difference of ϕms = –0.57V is required. For an aluminum -silicondioxide junction, ϕm = 3.21V and for a silicon-silicon dioxide junction = 3.20V and Eg = 1 .1 eV if the gate is Aluminum then the acceptor doping concentration to meet the specifications is_________ × 1010 cm–3 (upto two decimal places)(kT/q = 26 mV)

Question 21

A silicon abrupt junction in thermal equilibrium at T=300K is doped such that in n-region and in the p-region. Consider Nc = and Na =
What will be the impurity doping concentrations Nd and Na in n and p-regions and the built-in potential barrier, Vbi in the p-n junction respectively?

Question 22

Consider a silicon PN junction at T = 300 k with acceptor concentration of Na = 1018 cm–3 and donor concentration of Nd = 1015 cm–3. If we change the acceptor doping concentration to Na = 1016 cm–3 by keeping all other parameters constant, then the percentage decrease in built – in potential of the junction will be equal to ________ %.

(Assume ni = 1.5 × 1010 cm–3, kT = 0.026 eV)

Question 23

A uniformly doped silicon(relative permittivity εr=11.7) p-n junction has dopant profile of Na=Nd=5X1016 cm-3. If peak electric field in the junction at breakdown is E = 4X105 V/ cm, then breakdown voltage of this junction is ____V

Question 24Multiple Correct Options

An intrinsic semiconductor is doped with an impurity concentration of. Assume the intrinsic carrier concentrationand the thermal voltage. The Fermi level in doped semiconductor

Question 25Multiple Correct Options

A MOSFET carriers a drain current of 2 mA with VDS = 2V in saturation at λ = 0 what are the possible drain to source resistance when λ = 0.1 V–1 to λ = 0.3 V–1
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Jan 15ESE & GATE EC