# hw1b - that make your calculation easier Problem#4(2 pts...

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Homework #1 (ENEE 313 – Fall 2009; Horiuchi) Due Monday, Sept 14 th (in class) Problem #1 (2 pts) – atomic packing factor In class we found the atomic packing factor for fcc to be 0.74 and for the bcc to be 0.68. Show the reasoning and calculations for finding the atomic packing factor (fraction) for the simple cubic (sc) and the diamond crystal. (The majority of the points lie in your explanation of how you calculated this, not the final answer.) Helpful info: The angle between bonds is 109.5 degrees. Problem #2 (0.5 pt) – plane notation Give the Miller indices for the following planes: Problem #3 (2 pts) – de Broglie wavelength of speedy electrons What is the de Broglie wavelength of an electron at: a) 0.9 eV b) 9eV c) 90eV d) 900eV (Hint: Planck’s constant and the mass of an electron can be expressed in many different units. Find and pick units
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Unformatted text preview: that make your calculation easier.) Problem #4 (2 pts) – For each of the four materials introduced below, listed with their bandgap energies, calculate the shortest wavelength of light that will pass through the material without being absorbed. Give your answer in angstroms (1 Angstrom = 1E-10m) Aluminum antimonide, Eg = 1.63 eV Gallium phosphide, Eg = 2.24eV Zinc sulfide, Eg = 3.6eV Indium arsenide, Eg = 0.33eV Problem #5 (1 pt) – Visible light falls between 0.4um and 0.7um. For each of the four materials given above, determine whether it is transparent or opaque to visible light. Remember that photons are not absorbed if the energy of the light is less than the bandgap. If it is not all or none, indicate roughly what color you might expect it to be when looking through it at a source of white light. x y z x y z (a) (b)...
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