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Homework Help: Im convuesed help

  1. Aug 31, 2009 #1
    hi guys im quit confused n i have some problem that i realy need some one 2 solve them and 4 me
    the first prob

    1. A one dimensional infinite potential well with a width of 12A contains an electron.
    a. Calculate the first two energy levels that the electron may occupy
    b. If an electron drops from the second energy level to the first, what is the
    wavelength of a photon that might be emitted?

    2nd one

    If the temperature is 300K, determine the number of energy states available in GaAs
    a. Ec and Ec+kT
    b. Ev-kT and Ev

    and the last one

    Plot the function for Fermi-Dirac distribution for eV E E eV
    F − 0.5 ≤ ( − ) ≤ 0.5 for:
    a. T=200K
    b. T=300K
    c. T=400K
    Last edited: Aug 31, 2009
  2. jcsd
  3. Aug 31, 2009 #2


    User Avatar
    Gold Member

    hey weds, welcome to PF

    why don’t you show the related equations, and show your attempt to solve these problems, we’ll then help you :smile:
  4. Aug 31, 2009 #3
    oh i actually solve the first and the related equation 4 it is
    • Total energy
    h(square)x n(square)x π(square) / 2m a(square).....where a is the potential width which = 12x10(power of -10)
    substitute the values and i've got the answers
    answer: -13.58eV, -3.395eV, -1.51eV, -0.849eV]

    for the next quastion the related equation is
    • Density of state function in conduction band
    g Ec =(4π(2m(power of 3/2)) /h(power 3))x((root of)E-Ec)

    • Density of state function in valence band
    g Ev =(4π(2m(power of 3/2)) /h(power 3))x((root of)E-Ev)

    bt i dont knw how to substitute the value from the problem to the equqtion

    for the last prob
    the related equation is
    • Fermi-Dirac distribution function:
    f ( E) =1/exp(E-Ef/kT)
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