A Ga As device is doped with a donor concentration of 3*1010cm-3.For the device to operate properly, the intrinsic carrier concentration must remain less than 5% of the total concentration. The maximum temperature on which the device may operate is

1.  763K

2.  942K

3.  486K

4.  243K

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4
Correct Answer :

763K


Explanation :
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A silicon crystal having a cross sectional area of 0.001cm2 and a length of 20μm is connected to its ends to a 20v battery.At T=300K,we want a current of 100 mA in crystal.The concentration of donor atoms to be added is

1.  2.4*1013cm-3

2.  4.6*1013cm-3

3.  7.8*1014cm-3

4.  8.4*1014cm-3

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4
Correct Answer :

4.6*1013cm-3


Explanation :
No Explanation available for this question

An n-type silicon sample has a resistivity of 5 Ω-cm at T= 300K.If mobility is μn=1350 cm2/V-s, then donor impurity concentration is

1.  2.86*10-14cm-3

2.  9.25*1014cm-3

3.  11.46*1015cm-3

4.  1.1*10-15cm-3

View Answer  
4
Correct Answer :

9.25*1014cm-3


Explanation :
No Explanation available for this question

For a particular semiconductor material following parameters are observed : μn=1000cm2/V-s μp=600cm2/V-s Nc= Nv=1019cm-3 These parameters are independent of temperature. The measured conductivity of the intrinsic material is σ=10-6(Ω-cm)-1 at T=300K The conductivity at T=500K is

1.  2*10-4(Ω-cm)-1

2.  4*10-5(Ω-cm)-1

3.  2*10-5(Ω-cm)-1

4.  6*10-3(Ω-cm)-1

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4
Correct Answer :

6*10-3(Ω-cm)-1


Explanation :
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In a particular semiconductor the donor inpurity concentration is Nd=1014cm-3.Assume the following parameters μn=1000cm2/V-s Ne=2*1019(T/3000)3/2cm-3 Nv=1*1019(T/3000)3/2cm-3 Eg=1.1eV If an electric field of E=100V/cm is appiled, then electric current density at 300K is

1.  2.3A/cm2

2.  1.6 A/cm2

3.  9.6 A/cm2

4.  3.4 A/cm2

View Answer  
4
Correct Answer :

1.6 A/cm2


Explanation :
No Explanation available for this question

When conductivity is minimum, then whole concentration is

1.  7.2*1011cm-3

2.  1.8*1013cm-3

3.  1.44*1011cm-3

4.  9*1011cm-3

View Answer  
4
Correct Answer :

1.8*1013cm-3


Explanation :
No Explanation available for this question

Three scattering mechanism exist in a semiconductor. If only first mechanism were present,then mobility would be 750cm2/V-s.If only third mechanism were present, then mobility would be 1500 cm2/V-s.The net mobility is

1.  2750 cm2/V-s

2.  1114 cm2/V-s

3.  818 cm2/V-s

4.  250 cm2/V-s

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4
Correct Answer :

250 cm2/V-s


Explanation :
No Explanation available for this question

Expression for the output voltage V0 in terms of the input voltage V1 and V2 in the circuit shown in the figure, assuming operational amplifier to be ideal is V0=A1V1+A2V2 values of A1 and A2 would be respectively

1.  9 and -10

2.  -9 and 10

3.  9.9 and -10

4.   -9.9 and 10

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4
Correct Answer :

-9 and 10


Explanation :
No Explanation available for this question

A sample of N-type semiconductor has electron density of 6.25*1018/cm3 at 300K.If the intrinsic concentration of carriers in this sample is 2.25*1013/cm3, at this temperature, the hole density works out to be

1.  104/cm3

2.  104/cm3

3.  1010/cm3

4.  1012/cm3

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4
Correct Answer :

104/cm3


Explanation :
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The hole concentration in p-type GaAs is given by P=1016(1-x/L)cm-3 for 0≤x≤L Where L=10μm If hole diffusion coefficient is 10cm3/s, then hole diffusion current density at x=5 μm is

1.  20A/cm2

2.  16A/cm2

3.  24A/cm2

4.  30A/cm2

View Answer  
4
Correct Answer :

16A/cm2


Explanation :
No Explanation available for this question
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