20101ee2_1_Practice Problem Set 1

# 20101ee2_1_Practice Problem Set 1 - of the electron 5(a...

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Physics for Electrical Engineers P r o f . B . J a l a l i E E 2 Practice Problem Set #1 ( Please take a look before your next discussion session ) 1. How many electron states are there with energy between 1.0 eV and 1.2 eV in a rectangular box of dimensions 1cm, 2cm, and 3cm? 2. What is the probability that an electron state with energy 0.1 eV below the Fermi energy will be occupied at T= 0K, 100K, and 300K? 3. What is the probability that an electron state with energy 0.1 eV above the Fermi energy will be occupied at T= 0K, 100K, and 300K? 4. Suppose the energy is given by E ( k ) = 2.74 × 10 -37 k 2 joules where k is given in units of meter -1 . Find the effective mass, and give the ratio of the effective mass to the ordinary mass

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Unformatted text preview: of the electron. 5. (a) Explain why holes are found at the top of the valence band, whereas electrons are found at the bottom of the conduction band. (b) Explain why Si doped with 10 14 cm-3 Phosphorous is n-type at 400 K but similar doped Ge is not. 6. Si sample is doped with 6 X 10 15 cm-3 donors and 2 X 10 15 cm-3 acceptors. Find the position of the Fermi level with respect to E i at 300 K. 7. Solar cell problem: Fig 1 shows the solar spectral irradiance area (unit: W/m 2 nm) vs different wavelengths (unit: nm). Please calculate the percentage of the sun’s power that will be absorbed into the silicon. (Assume Eg=1.24eV)....
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20101ee2_1_Practice Problem Set 1 - of the electron 5(a...

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