501. Threshold voltage of MOSFET can be lowered by:
     (i) Reducing doping in substrate
     (ii) Increasing doping in substrate
     (iii) Decreasing gate oxide thickness
     The correct statement are—

1. 1. (iii) only

   
   
   

   2. (i) and (iii) only

   
   
   

   3. (i) and (ii) only

   
   
   

   4. (ii) only

   
   
   

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   NA

   Correct Option: A

   NA

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502. Consider the following steps—
     (1) Exposure to UV radiation
     (2) Etching
     (3) Stripping
     (4) Developing After coating with photoresist,
     the correct sequence of steps in photolithography—

1. 1. 2, 4, 3, 1

   
   
   

   2. 4, 2, 3, 1

   
   
   

   3. 1, 4, 2, 3

   
   
   

   4. 1, 2, 3, 4

   
   
   

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   NA

   Correct Option: C

   NA

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503. High threshold MOSFET can be obtained by using silicon crystal orientation—

1. 1. <100>

   
   
   

   2. <101>

   
   
   

   3. <110>

   
   
   

   4. <111>

   
   
   

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   NA

   Correct Option: C

   NA

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504. Germanium—

1. 1. Can’t be purified by zone refling

   
   
   

   2. Usually purified by floating zone method

   
   
   

   3. More easily purified than Si

   
   
   

   4. Has melting point higher than Si
      

   
   
   

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   NA

   Correct Option: C

   NA

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505. For a circuit containing both pnp and npn transistors the monolithic IC requires—

1. 1. 3 layers

   
   
   

   2. 5 layers

   
   
   

   3. 6 layers

   
   
   

   4. 4 layers

   
   
   

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   NA

   Correct Option: C

   NA

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