# In a semi conductor at room temperature (3000K), the intrinsic Carrier concentration and resistivity are 1.5 x 1016/m3 and 2 x 103 Ω-m respectively. It is concerted into an extrinsic semi conductor with a doping concentration of 1020/m3 for the extrinsic semiconductor calculate the a. Minority carrier concentration b. Resistivity of extrinsic semiconductor c. Shift in fermilevel due to doping d. Minority concentration if intrinsic carrier concentration doubles Assume i. The mobility of minority and majority carries to be the same ii. KT=26mV at room temperature

1.   a. 2.25X1012/m3, b. 4.80X10-5Ω-m, c. 0.228 ev

2.  a. 2.00X1012/m3, b. 4.00X10-5Ω-m, c. 0.200 ev

3.  a. 1.25X1012/m3, b. 3.15X10-5Ω-m, c. 0.15 ev

4.  a. 1.00X1012/m3, b. 3.00X10-5Ω-m, c. 0.11 ev

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a. 2.25X1012/m3, b. 4.80X10-5Ω-m, c. 0.228 ev

Explanation :
No Explanation available for this question

# In a junction diode

1.  The depletion capacitance increases with increase in the reverse bias

2.  The depletion capacitance decreases with increase in the reverse bias

3.  The depletion capacitance increases with increase in the forward bias

4.  The depletion capacitance much higher than the depletion capacitance when it is forward biased

4

The depletion capacitance decreases with increase in the reverse bias

Explanation :
No Explanation available for this question

# A silicon PN junction biased with a constant at room temperature. When the temperature is increased by 100C, the forward bias voltage across the PN junction

1.  Increases by 60 mV

2.  Deceases by 60 mV

3.  Increases by 25 mV

4.  Decreases by 25 mV

4

Decreases by 25 mV

Explanation :
No Explanation available for this question

# A zener diode, when used in voltage stabilization circuits, is biased in

1.  Reverse bias region below the breakdown voltage

2.  Reverse breakdown region

3.   Forward bias region

4.  Forward bias constant current mode

4

Reverse breakdown region

Explanation :
No Explanation available for this question

# In a forward biased pm junction diode, the sequence of events that best describes the mechanism of current flow is

1.   Injection and subsequent diffusion and recombination of minority carriers

2.  Injection and subsequent drift and generation of minority carriers

3.  Extraction, and subsequent diffusion and generation of minority carriers

4.  Extraction, and subsequent drift and recombination of minority carriers

4

Injection and subsequent diffusion and recombination of minority carriers

Explanation :
No Explanation available for this question

# In a uniformly doped abrupt p-n  junction the doping level of the n-side is four times the doping level of the p-side the ratio of the depletion layer width of n-side verses p-side is

1.   0.25

2.   0.5

3.  1.0

4.  2.0

4

0.25

Explanation :
No Explanation available for this question

# The small signal capacitance of an abrupt p+n junction is 1 nf/Cm2 at zero bias. If the built-in voltage is 1 volt, the capacitance at a reverse bias voltage of 99 volts in

1.   10

2.   0.1

3.   0.01

4.  100

4

0.1

Explanation :
No Explanation available for this question

# In the circuit shown below, the knee current of the ideal Zener diode is 10 mA. To maintain 5 V across RL, the minimum value of RL in Ω and the minimum power rating of the Zener diode in mW, respectively, are

1.  125 and 125

2.   125 and 250

3.  250 and 125

4.   250 and 250

4

125 and 250

Explanation :
No Explanation available for this question

# A voltage 1000sinωt Volts is applied across YZ. Assuming ideal diodes the voltage measured across WX in Volts, is

1.   sin ωt

2.  (sin ωt +|sin ωt|)/2

3.   (sin ωt-|sin ωt|)/2

4.  0 for all t

4

0 for all t

Explanation :
No Explanation available for this question

# For the circuit shown in the figure D1 and D2 are identical diodes with ideality factor of unity. The thermal voltage VT=25 mV a. Calculate VT and Vr b. If the reverse saturation current of D1 and D2 are 1pA then compute the current

1.  (a)32.68 mV, (b).0.99 pA

2.  (a)30.68 mV, (b).0.55 pA

3.  (a)32.00 mV, (b).0.44 pA

4.  (a)30.00 mV, (b).0.33 pA

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