To obtain electrons as majority charge carriers in a semiconductor, the impurity mixed is 

  • Monovalent         

  • Divalent

  • Trivalent               

  • Pentavalent

For germanium crystal, the forbidden energy gap in joules is

  • (1) 1.12×10-19        

  • (2) 1.76×10-19

  • (3)  1.6×10-19         

  • (4) Zero

A pure semiconductor behaves slightly as a conductor at

  • Room temperature             

  • Low temperature

  • High temperature               

  • Both (b) and (c)

Which is the correct relation for the forbidden energy gap in the conductor, semiconductor, and insulator

  • ∆Egc<∆Eginsulator<∆Egsc

  • ∆Egc<∆Egsc<∆Eginsulator

  • ∆∆Egsc<∆Eginsulator<Egc

  • ∆Egsc<∆Ec<∆Eginsulator

At room temperature, a P-type semiconductor has
  • Large number of holes and few electrons

  • Large number of free electrons and few holes

  • Equal number of free electrons and holes

  • No electrons or holes

The energy band gap is maximum in

  • Semiconductors

  • Metals               

  • Superconductors

  • Insulators         

The process of adding impurities to the pure semiconductor is called 
  • Drouping       

  • Drooping

  • Doping           

  • None of these

To a germanium sample, traces of gallium are added as an impurity. The resultant sample would behave like

  • A conductor

  • A P-type semiconductor

  • An N-type semiconductor

  • An insulator

Donor type impurity is found in 

  • Trivalent elements       

  • Pentavalent elements

  • In both the above       

  • None of these

The difference in the variation of resistance with temperature in a metal and a semiconductor arises essentially due to the difference in the 

  • Variation of scattering mechanism with temperature

  • Crystal structure

  • Variation of the number of charge carriers with temperature

  • Type of bond

The charge on a hole is equal to the charge of
  • Zero               

  • Proton

  • Neutron         

  • Electron

A Ge specimen is doped with Al. The concentration of acceptor atoms is ~1021 atoms/m3. Given that the intrinsic concentration of electron hole pairs is ~1019/m3, the concentration of electrons in the specimen is 

  • 1017/m3

  • 1015/m3

  • 104/m3

  • 102/m3

Which of the following has negative temperature coefficient of resistance 

  • Copper               

  • Aluminium

  • Iron                   

  • Germanium

In semiconductors at a room temperature 

  • The valence band is partially empty and the conduction band is partially filled

  • The valence band is completely filled and the conduction band is partially filled

  • The valence band is completely filled

  • The conduction band is completely empty

Regarding a semiconductor which one of the following is wrong 

  • There are no free electrons at room temperature

  • There are no free electrons at 0 K

  • The number of free electrons increases with rise of temperature

  • The charge carriers are electrons and holes

Which of the following statements is true for an N-type semi-conductor 

  • The donor level lies closely below the bottom of the conduction band

  • The donor level lies closely above the top of the valence band

  • The donor level lies at the halfway mark of the forbidden energy gap

  • None of above

Choose the correct statement

  • When we heat a semiconductor its resistance increases

  • When we heat a semiconductor its resistance decreases

  • When we cool a semiconductor to 0 K then it becomes super conductor

  • Resistance of a semiconductor is independent of temperature

Intrinsic semiconductor is electrically neutral. Extrinsic semiconductor having large number of current carriers would be 

  • Positively charged

  • Negatively charged

  • Positively charged or negatively charged depending upon the type of impurity that has been added

  • Electrically neutral

If ne and vd be the number of electrons and drift velocity in a semiconductor. When the temperature is increased
  •  ne increases and vd decreases

  •  ne decreases and vd increases

  • Both ne and vd increases

  • Both ne and vd decreases

The energy gap of silicon is 1.14 eV. The maximum wavelength at which silicon will begin absorbing energy is
  • 10888 Å                   

  • 1088.8 Å

  • 108.88 Å                   

  • 10.888 Å

Which of the following energy band diagram shows the N-type semiconductor

 

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  •  

  •  

  •  

Which of the energy band diagrams shown in the figure corresponds to that of a semiconductor

 

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  •  

The energy band diagrams for three semiconductor samples of silicon are as shown. We can then assert that

  • Sample X is undoped while samples Y and Z have been doped with a third group and a fifth group impurity respectively

  • Sample X is undoped while both samples Y and Z have been doped with a fifth group impurity

  • Sample X has been doped with equal amounts of third and fifth group impurities while samples Y and Z are undoped

  • Sample X is undoped while samples Y and Z have been doped with a fifth group and a third group impurity respectively

In a semiconducting material, the mobilities of electrons and holes are μe and μh respectively. Which of the following is true?
  • μe>μh               

  •   μe<μh

  •   μe= μh             

  •   μe<0; μh>0

In a forward biased P-N junction diode, the potential barrier in the depletion region is of the form

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Different voltages are applied across a P-N junction and the currents are measured for each value. Which of the following graphs is obtained between voltage and current?

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If the following input signal is sent through a PN-junction diode, then the output signal across RL will be

 

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The curve between charge density and distance near P-N junction will be

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The resistance of a germanium junction diode whose is shown in figure is Vk=0.3V
  • 5 kΩ

  • 0.2 kΩ

  • 2.3 kΩ

  • 102.3kΩ

In the half-wave rectifier circuit shown. Which one of the following wave forms is true for VCD, the output across C and D?

  •  

  •  

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