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4. Consider a piece of silicon A is doped with both donor and acceptor impurities as: $N_D = 2.5 \times 10^{15} \text{cm}^{-3}$ and $N_A = 1.3 \times 10^{13} \text{cm}^{-3}$. Another piece of silicon B is doped with only donors $N_D = 1.2 \times 10^{13} \text{cm}^{-3}$. Assuming complete ionization of impurities and the intrinsic carrier concentration $n_i = 10^{10} \text{cm}^{-3}$. Which of the following statement is true? (4 points) a) Electron concentration in sample A > sample B b) Electron concentration in sample A < sample B c) Electron concentration in sample A is approximately equal to sample B d) Additional information is needed. 5. Two semiconductor materials have exactly the same properties except that material A has a band gap value of 1.0 eV and material B has a band gap value of 1.2 eV. Determine the ratio of the intrinsic carrier concentration $n_i$ of material A to that of material B at room temperature. (4 points) a) 32.4 b) 2191.4 c) 46.8 d) 75.3 6. What is the charge state of an occupied donor (i.e., a donor atom has been occupied by an electron) and what is the charge state of an unoccupied acceptor (i.e., an acceptor atom has not been occupied by an electron)? (4 points) a) Neutral, positive

          4. Consider a piece of silicon A is doped with both donor and acceptor impurities as: $N_D = 2.5 \times 10^{15} \text{cm}^{-3}$ and $N_A = 1.3 \times 10^{13} \text{cm}^{-3}$. Another piece of silicon B is doped with only donors $N_D = 1.2 \times 10^{13} \text{cm}^{-3}$. Assuming complete ionization of impurities and the intrinsic carrier concentration $n_i = 10^{10} \text{cm}^{-3}$. Which of the following statement is true? (4 points)
a) Electron concentration in sample A > sample B
b) Electron concentration in sample A < sample B
c) Electron concentration in sample A is approximately equal to sample B
d) Additional information is needed.
5. Two semiconductor materials have exactly the same properties except that material A has a band gap value of 1.0 eV and material B has a band gap value of 1.2 eV. Determine the ratio of the intrinsic carrier concentration $n_i$ of material A to that of material B at room temperature. (4 points)
a) 32.4
b) 2191.4
c) 46.8
d) 75.3
6. What is the charge state of an occupied donor (i.e., a donor atom has been occupied by an electron) and what is the charge state of an unoccupied acceptor (i.e., an acceptor atom has not been occupied by an electron)? (4 points)
a) Neutral, positive

4. Consider a piece of silicon A is doped with both donor and acceptor impurities as: ND = 2.5 × 10^15cm^-3 and NA = 1.3 × 10^13cm^-3. Another piece of silicon B is doped with only donors ND = 1.2 × 10^13cm^-3. Assuming complete ionization of impurities and the intrinsic carrier concentration ni = 10^10cm^-3. Which of the following statement is true? (4 points)
a) Electron concentration in sample A > sample B
b) Electron concentration in sample A < sample B
c) Electron concentration in sample A is approximately equal to sample B
d) Additional information is needed.
5. Two semiconductor materials have exactly the same properties except that material A has a band gap value of 1.0 eV and material B has a band gap value of 1.2 eV. Determine the ratio of the intrinsic carrier concentration ni of material A to that of material B at room temperature. (4 points)
a) 32.4
b) 2191.4
c) 46.8
d) 75.3
6. What is the charge state of an occupied donor (i.e., a donor atom has been occupied by an electron) and what is the charge state of an unoccupied acceptor (i.e., an acceptor atom has not been occupied by an electron)? (4 points)
a) Neutral, positive

Added by Juan Antonio R.

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