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Wave Optics

Question
CBSEENPH12039965

Pure Si at 500 K has an equal number of the electron (ne) and hole (nh) concentrations of 1.5 x 1016 m-3.Doping by indium increases nh to 4.5 x 1022 m -3.The doped semiconductor is of 

  • n- type with electron concentration ne = 5 x 1022 m -3

  • P- type with electron concentration ne = 2.5 x 1010 m -3

  • n- type with electron concentration ne = 2.5 x 1023 m -3

  • p- type with electron concentration ne = 5 x 109-3

Solution

D.

p- type with electron concentration ne = 5 x 109-3

straight n subscript straight i superscript 2 space equals space straight n subscript straight e straight n subscript straight h
straight n subscript straight e space equals fraction numerator left parenthesis straight n subscript straight i right parenthesis squared over denominator straight n subscript straight h end fraction

straight n subscript straight e space equals space fraction numerator left parenthesis 1.5 space straight x space 10 to the power of 16 right parenthesis squared over denominator 4.5 space straight x space 10 to the power of 22 end fraction

straight n subscript straight e space equals space 5 space straight x space 10 to the power of 9 space straight m to the power of negative 3 end exponent

So comma space straight n subscript straight h space greater than greater than space straight n subscript straight e space semiconductor space is space straight p minus type

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