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In the figure below the absorption coefficient as a function of the wavelength for several semiconductor materials is presented. Let's consider monochromatic light of photons with energy of Eph=1.55eV that incidents a film with thickness d. If we ignore possible reflection losses at the rear and front interfaces of the film, what thickness d (in μm) is required to achieve a light absorption of 90%?



UPDATE: Since it was very difficult to accurately read off the absorption coefficient values from the graph above, we have chosen to provide you with these values. The absorption coefficients for the different semiconductor materials at α(800nm) are:

αGaAs=2∗104cm−1
αInP=4∗104cm−1
αGe=6∗104cm−1
αSi=1∗103cm−1.

The thickness d (in μm) required to achieve a light absorption of 90% is:

1) For GaAs


2) For InP


3) For Ge


4) For Si

asked by Anonymous
  1. I am also stuck at that question and can not solve it ... if you have the answer or at least some clue how can I solve it - please share!

    posted by kv
  2. users . encs. concordia. ca/~mojtaba/ ELEC425- assignment4- solutions . pdf


    edit the spaces

    posted by a
  3. Can you please just give out the answers.. thanx!!

    posted by Anonymous
  4. please help in this q?

    posted by Anonymous
  5. i am also stuck plz help

    posted by insha
  6. 1.1513
    0.5756
    0.383764
    23.026
    ;)

    posted by Sason
  7. I think 1.51, not 1.15

    posted by I.G.
  8. 1.1513
    0.5756
    0.383764
    23.026

    posted by r k

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