Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Problem related to nanotechnology

  1. Sep 10, 2011 #1
    1. In a quantum dot nanostructure having aside of 10 nm has donor concentration 1018
    cm-3 . Calculate conduction electron contentin the quantum-dot. Also calculate the
    electron content in it if the concentration is1014 .

    2. Consider the bulk crystal of GaAs with an electron effective mass m* = 0.067 m0 ,
    where m0 is the free-electron mass. Calculate the de Broglie wavelength for free as well as
    electron with effective mass m* .

    3. Assume that an electron with m0 = 9.8*10-31 kg is placed in a quantum well with two
    impenetrable walls and that the distance between the walls is LO = 10 cm. Calculate
    the three lowest sub-band bottom energies: ε1 ,ε2 ,ε3. For these stationary states, find the
    probability density of finding the electron at the middle of the well at z = 0.

    4. Using the lattice constant of silicon, a = 5.43* 10-8 , and the fact that the number of Si
    atoms per unit volume, a3 , is eight, calculate the number of atoms per 1 cm3 and the
    density of the crystalline silicon ( silicon’s atomic weight is 28.1 g mol-1 ).

    5. Assume that the conduction-band offset for an AlGaAs heterojunction is 60% of the difference of the band gaps of these materials. Find the composition of the AlGaAs layer necessary for the resulting heterojunction to have an energy barrier for the
    electrons to .3 eV. Calulate the energy barrier for the holes. Given that the band gap energy E of the alloy AlxGa1-xAs is given as Δg = 1.42 + 1.247 x and the
    band gap energy for the GaAs is Δg = 1.42 eV.

    6. For AlxGa1-xAs alloy, find the composition having an
    energy bandgap equal to 2 eV. For this alloy,
    determine the effective masses in the Г and X valleys.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?