Physical electronics devices and ics miscellaneous

Physical electronics devices and ics miscellaneous

Easy Questions

Physical Electronics Devices and ICs

Physical electronics devices and ics miscellaneous
  1. In a Hall effect experiment, a p-type semiconductor sample with hole concentration p1 is used. The measured value of the Hall voltage is VH1. If the p-type sample is now replaced by another p-type sample with hole concentration p2 where p2 = 2p1. What is the net Hall voltage VH2?








  1. View Hint View Answer Discuss in Forum

    We know that hall voltage is inversely proportional to the concentration i.e.,

    VH
    1
    Concentration

    Therefore,
    VH1
    		=
    P2
    VH2P1

    Therefore,
    VH1
    		=
    P2
    VH2P1

    or VH2=
    P1
    		x VH1 =
    1
    		 VH1
    VH22

    Hence alternative (C) is the correct choice.

    Correct Option: C

    We know that hall voltage is inversely proportional to the concentration i.e.,

    VH
    1
    Concentration

    Therefore,
    VH1
    		=
    P2
    VH2P1

    Therefore,
    VH1
    		=
    P2
    VH2P1

    or VH2=
    P1
    		x VH1 =
    1
    		 VH1
    VH22

    Hence alternative (C) is the correct choice.

  1. An intrinsic semiconductor with energy gap 1 eV has a carrier concentration N at temperature 200 K. Another intrinsic semiconductor has the same value of carrier concentration N at temperature 600 K. What is the energy gap value for the second semiconductor?








  1. View Hint View Answer Discuss in Forum

    Given Eg1 = 1eV, T1 = 200 K, T2 = 600 K, Eg2 =?

    Eg1
    		=
    T2
    Eg2T1

    Where Eg = Energy band gap
    T = Temperature
    Now, Eg2 = Eg1 ×
    T1
    T2

    = 1eV ×
    200 K
    		=
    1eV
    600 K3

    Hence alternative (D) is the correct choice.

    Correct Option: A

    Given Eg1 = 1eV, T1 = 200 K, T2 = 600 K, Eg2 =?

    Eg1
    		=
    T2
    Eg2T1

    Where Eg = Energy band gap
    T = Temperature
    Now, Eg2 = Eg1 ×
    T1
    T2

    = 1eV ×
    200 K
    		=
    1eV
    600 K3

    Hence alternative (D) is the correct choice.

  1. Which of the following can be determined by using a Hall crystal?
    1. Concentration of holes in a p-type semiconductor.
    2. Concentration of electrons in an n-type semiconductor.
    3. Temperature of a the set-up with any type of semiconductor.
    4. Diffusion constant and life-time of minority carriers of any type of semiconductor.
    Select the correct answer using the code given below:








  1. View Hint View Answer Discuss in Forum

    Hall effect is used to determine whether a semiconductor is n-type or p-type and to find the carrier concentration. Hence alternative (A) is the correct choice.

    Correct Option: A

    Hall effect is used to determine whether a semiconductor is n-type or p-type and to find the carrier concentration. Hence alternative (A) is the correct choice.

  1. The electron concentration in a silicon sample doped with 1015 cm– 3 P atoms, will vary, in the temperature range of 4·2 – 1000 K, as follows—








  1. View Hint View Answer Discuss in Forum

    The electron concentration in a silicon sample doped with 1015 cm–3 atoms will first increases exponentially upto a temperature T1 then remain constant at 1015 cm–3 upto a temperature T2 and then increases exponentially. Since, as the temperature is raised, the donar electrons are donated to the conduction band and at temperature T1 all the donar atoms are ionized. This temperature range is called the ionization region in which electron concentration increases exponentially.
    When every available extrinsic electron has been transferred to the conduction band, the conduction band electron concentration n0 is virtually constant with temperature until the concentration of extrinsic carriers ni becomes comparable to the extrinsic concentration Nd.
    Finally at higher temperature, ni is much greater than Nd and the intrinsic carriers dominate. The electron concentration increases exponentially again now as

    ni2 = AT 3e
    -Eg
    KT

    The above concept can be better understood by the figure shown below—


    Correct Option: D

    The electron concentration in a silicon sample doped with 1015 cm–3 atoms will first increases exponentially upto a temperature T1 then remain constant at 1015 cm–3 upto a temperature T2 and then increases exponentially. Since, as the temperature is raised, the donar electrons are donated to the conduction band and at temperature T1 all the donar atoms are ionized. This temperature range is called the ionization region in which electron concentration increases exponentially.
    When every available extrinsic electron has been transferred to the conduction band, the conduction band electron concentration n0 is virtually constant with temperature until the concentration of extrinsic carriers ni becomes comparable to the extrinsic concentration Nd.
    Finally at higher temperature, ni is much greater than Nd and the intrinsic carriers dominate. The electron concentration increases exponentially again now as

    ni2 = AT 3e
    -Eg
    KT

    The above concept can be better understood by the figure shown below—


  1. Photons of energy 1·53 × 10– 19 joule are incident on a photodiode which has a respectivity of 0·65 A/W. If the optical power level is 10 µW, what is the photocurrent generated?








  1. View Hint View Answer Discuss in Forum

    Responsivity, R = 0·65 A/ W
    P0 = Incident optical power
    = 10 µW

    Responsivity, R =
    Ig
    Po

    or Ip = R·P0
    = 0·65 A/W × 10 µW = 6·5 µA
    Hence alternative (D) is the correct choice.

    Correct Option: D

    Responsivity, R = 0·65 A/ W
    P0 = Incident optical power
    = 10 µW

    Responsivity, R =
    Ig
    Po

    or Ip = R·P0
    = 0·65 A/W × 10 µW = 6·5 µA
    Hence alternative (D) is the correct choice.