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quz1E_sol_corrected - Ans type n cm p n n o i o − ⇒ = =...

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ECE 440: Quiz Section E (1:00 p.m.) Name:_______________________________ 1. (a) For a III-V binary compound semiconductor (zinc-blende), the lattice constant is L in the unit of Angstrom. What is the minimum inter-atomic distance in this material? (2 points) Ans: The zinc-blende lattice is almost identical to the FCC lattice except that there is an additional interpenetrating FCC structure that is translated by (¼, ¼, ¼) x L. Thus, the minimum inter-atomic distance will be L L L L 4 3 4 1 4 1 4 1 2 2 2 = + + (b) Calculate the volume density (atoms/cm 3 ) of the column V atoms in the material. (3 points) Ans: There is 4 column V atoms in each unit cell with length L in the unit of Angstrom). So, density = 4 / ( L × 10 -8 ) 3 = 4 × 10 24 / L 3 (atoms/cm 3 ) 2. The hole concentration in InAs at T = 300 K is p 0 = 1 x 10 13 cm -3 and the intrinsic carrier concentration is 10 15 cm -3 . (a) Is this material n-type or p-type? (1point)
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Unformatted text preview: Ans: ( ) ( ) type n cm p n n o i o − ⇒ = = = − 3 17 13 2 2 10 10 10 15 (b) Sketch the band diagram of the sample, cal culating and labeling the difference between the various energy levels ( E C , E V , E F , E i ). (3points) Ans: (c) Is the probability of finding an electron at the energy level E = E C closer to zero or one? (1 point) Ans: According to Fig. 3-15, the probability is closer to “zero”. 3. On the energy diagram shown below: (a) Among electrons (1), (3) and (4), which one or ones has the highest total energy? (2 points) Ans: According to the diagram, Electron (3) has the highest total energy. (b) Rank the electrons (1), (3), and (4) in descending order of their kinetic energy. (3 points) Ans: Electron (4), (3), (1) in descending order (1) (3) (4) (1') (3') (4') E F x 1 x 2 x 3 x 4 x 5 X E c E v E i E F E g E g /2 Total Electron Energy E Kinetic Energy...
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