Home
Class 12
PHYSICS
The energy of a photon of sodium light (...

The energy of a photon of sodium light `(lambda=589 nm)`equal the band gap of a semiconducting material.(a)Find the minimum energy E requried to create a hole-electron pair.(b)Find the value of `E//kT`at a temperature of 300K.

Text Solution

Verified by Experts

The energy of the photon in `eV=(12400)/(lambda)`
Wavelength of photon `=589nm=5890Å`
`=(12400)/(5890)=2.1eV`
Thus the band gap is 2.1 eV . This is also the minimum energy E required to push an electron from the valence band into the conduction band . Hence , the minimum energy required to create a hole - electron pair is 2.1eV .
(b) At `T=300K, kT=(8.62xx10^(-5)eV//K)/(300K)`
`=25.86xx10^(-3)eV`.
Thus, `(E)/(kT)=(2.1eV)/(25.86xx10^(-3)eV)=81`
The available thermal energy is nearly 81 times less than that of the required energy to create electron hole pair . So it is difficult for the thermal energy to create the hole - electron pair but a photon of light can do it easily .
Doubtnut Promotions Banner Mobile Dark
|

Topper's Solved these Questions

  • SEMICONDUCTOR DEVICES

    AAKASH SERIES|Exercise EXERCISE - IA|54 Videos
  • SEMICONDUCTOR DEVICES

    AAKASH SERIES|Exercise EXERCISE - IB|7 Videos
  • SEMICONDUCTOR DEVICES

    AAKASH SERIES|Exercise PRACTICE EXERCISE (LOGIC GATES )|15 Videos
  • RAY OPTICS

    AAKASH SERIES|Exercise PROBLEMS ( LEVEL-II)|60 Videos
  • UNITS AND MEASUREMENT

    AAKASH SERIES|Exercise PRACTICE EXERCISE|45 Videos

Similar Questions

Explore conceptually related problems

find the maximum wavelength of electromagnetic radiation which can create a hole-electron pair in germanium.The band gap in germanium is 0.65eV.

The binding energy of an electron in the gorund state of He atom is equal to E_0 = 24.6 eV. Find the energy required to remove both electrons form the atom.

Knowledge Check

  • If the energy of a photon of sodium light ( lambda =589 nm) equals the band gap of semiconductor, the minimum energy required to create hole electron pair

    A
    1.1 eV
    B
    2.1 eV
    C
    3.2 eV
    D
    1.5 eV
  • The binding energy of the electron in the ground state of He atom is equal to E_(0)=24.6 eV . Find the energy required to remove both the electrons from the atom.

    A
    49.2eV
    B
    54.4eV
    C
    79eV
    D
    108.8eV
  • Find the wavelength of light that may excite an electron in the valence band of diamond to the conduction band. The energy gap is 5.50 eV

    A
    226 nm
    B
    312 nm
    C
    432 nm
    D
    550 nm
  • Similar Questions

    Explore conceptually related problems

    Statement (A): Every photon striking the metal and colliding with the electron uses part of its energy to remove the electron from the metal surface, the remaining part is used to impart K.E. to the electron. Statement (B): The minimum energy needed to remove the electron from the metal surface is called work function. Statement (C): There is no time lag between incidence of photon and emission of photoelectrons.

    An electron is orbiting is a circular orbit of radius r under the influence of a constant magnetic field of strength B. Assuming that Bohr postulate regarding the quantisation of angular momentum holds good for this elerctron, find (a) the allowed values of te radius r of the orbit. (b) the kinetic energy of the electron in orbit (c ) the potential energy of insteraction between the magnetic moment of the orbital current due to the electron moving in its orbit and the magnetic field B. (d) the total energy of the allowed energy levels. (e) the total magnetic flux due to the magnetic field B passing through the nth orbit. (Assume that the charge on the electronis -e and the mass of the electron is m).

    Light form a dicharge tube containing hydrogen atoms falls on the surface of a piece of sodium. The kinetic energy of the fastest photoelectrons emitted from sodium is 0.73 eV. The work function for sodium is 1.82 eV. Find (a) the energy of the photons causing the photoelectrons emission. (b) the quatum numbers of the two levels involved in the emission of these photons. (c ) the change in the angular momentum of the electron in the hydrogen atom, in the above transition, and (d) the recoil speed of the emitting atom assuming it to be at rest before the transition. (lonization potential of hydrogen is 13.6 eV.)

    The wavelength of light from the spectral emission line of sodium is 589 nm. Find the kinetic energy at which A neutron, and would have the same de Broglie wavelength.

    The wavelenths gamma of a photon and the de-Broglie wavelength of an electron have the same value.Find the ratio of energy of photon to the kinetic energy of electron in terms of mass m, speed of light and planck constatn