Modern Physics
3rd Edition
ISBN: 9781111794378
Author: Raymond A. Serway, Clement J. Moses, Curt A. Moyer
Publisher: Cengage Learning
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Chapter 12, Problem 4Q
To determine
Explain about the band structures of metals insulators and semiconductors and tell how the band model give better understanding about the electrical properties.
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Students have asked these similar questions
In a certain semiconductor, the valence band can be approximated by the function E(k) = Eo ak² and the
conduction band can be described by the function E(k)= E₁ + 3k². Here E(k) is the electron energy and k is the
wavevector. Plot E(k) for the two bands. What is the bandgap of this semiconductor? Is this a direct
or indirect bandgap semiconductor?
A20. An intrinsic silicon semiconductor is uniformly doped with acceptors to a level
of 2x1017 cm-³. At room temperature, the electron concentration in this
semiconductor is found to be 5x10² cm-3. What is the intrinsic carrier
concentration of this semiconductor at room temperature and describe
qualitatively how would the electron concentration change if the temperature
increased slightly?
exist is for valence electrons to "leap" into the conduction band with the
Enoiteou
Question 5
pplication of sufficient energy, legving a hole, or vacancy, behind in the
valence band:
Valence electron leaping
into conduction band
Conduction band
valence band
With sufficient thermal energy, these electron-hole pairs will form spontaneously.
Af room temperature, however, this activity is slight.
we may greatly enhance charge carrier formation by adding specific impurities
to the semiconducting material. The energy states of atoms having different
electron configurations do not precisely "blend" with the electron bands of the
parent semiconductor crystal, causing additional energy levels to form.
Some types of impurities will cause extra donor electrons to lurk just beneath the
main conduction band of the crystal. These types of impurities are called
pentavalent, because they have 5 valence electrons per atom rather than 4 as
the parent substance typically possesses:
Doped with a…
Chapter 12 Solutions
Modern Physics
Ch. 12 - Prob. 1QCh. 12 - Prob. 2QCh. 12 - Prob. 3QCh. 12 - Prob. 4QCh. 12 - Prob. 5QCh. 12 - Prob. 6QCh. 12 - Prob. 7QCh. 12 - Prob. 8QCh. 12 - Prob. 9QCh. 12 - Prob. 11Q
Ch. 12 - Discuss the differences between crystalline...Ch. 12 - Prob. 13QCh. 12 - Prob. 15QCh. 12 - Prob. 16QCh. 12 - Prob. 17QCh. 12 - Prob. 19QCh. 12 - Prob. 21QCh. 12 - Prob. 22QCh. 12 - Prob. 1PCh. 12 - Prob. 2PCh. 12 - Prob. 3PCh. 12 - Prob. 4PCh. 12 - Prob. 5PCh. 12 - Prob. 6PCh. 12 - Prob. 7PCh. 12 - The Madelung constant for the NaCl structure may...Ch. 12 - Prob. 9PCh. 12 - Prob. 10PCh. 12 - Prob. 11PCh. 12 - Prob. 12PCh. 12 - Prob. 13PCh. 12 - Prob. 15PCh. 12 - Prob. 16PCh. 12 - Prob. 18PCh. 12 - Prob. 19PCh. 12 - Prob. 20PCh. 12 - Prob. 21PCh. 12 - Determine the current generated in a...Ch. 12 - Prob. 23PCh. 12 - Under pressure, liquid helium can solidify as each...Ch. 12 - Prob. 25P
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- In the band theory of solids, if, at T = 0 K, the uppermost band to have electrons is completely filled, and the gap between that band and the next lowest band is 8 eV, is the material a metal, an insulator, or a semiconductor? and explain using band level diagram. What if the gap is 0.8 eV?arrow_forwardGermanium is a semiconductor. With the aid of diagrams showing bands of molecular orbital, explain why it is a poor conductor and how doping it with phosphorus increases its conductivity.arrow_forwardMost solar cells are semiconductor-based. If most solar radiation has a wavelength of less than 1m, what should the band gap of the solar cell material be? Silicon has a band gap of 1.14 eV. Is silicon a suitable solar cell material?arrow_forward
- The figure below shows a portion of the energy band diagram of a p-n semiconductor junction. According to the situation shown in the figure, in the equilibrium condition, we can identify the currents as follows:(a) i1:electron diffusion current, i2:electron drift current, i3:hole diffusion current and i4:hole drift current. (b) i1:hole drift current, i2:electron drift current, i3:hole diffusion current and i4:electron diffusion current. (c) i1:hole diffusion current, i2:electron drift current, i3:hole drift current and i4:electron diffusion current. (d) i1:electron diffusion current, i2:electron diffusion current, i3:hole drift current and i4:hole drift current. (e) i1:hole drift current, i2:electron diffusion current, i3:hole diffusion current and i4:electron drift current.arrow_forwardhow does a semiconductor behaves at 0K? Explain your answer.arrow_forwardDescribe an extrinsic semiconductor material. What is the value or the electron concentration in an n-type material, and what is the value of the hole concentration in a p-type material?arrow_forward
- A typical television remote control uses signal from an infrared LED. If the infrared light has a wavelength of 900 nm,(a). What is the energy band gap of the semiconductor in the LED? (b). What is the working principle of a semiconductor LED?arrow_forwardFor Ge semiconductor, assume the Fermi energy level is 0.15 eV below the conduction band energy Ec. Let the absolute temperature T for items i and ii be 200 K. i. Find the number of quantum states between Ec and Ec + 5 x KbT. ii. Determine the probability of a state being empty of an electron at Ec + 5 x KbT. ii. Find the temperature at which there is an electron at the state Ec + 0.5 x KbT with probability 30%. iv. Repeat item ii by using the Boltzmann approximation rather than the Fermi-Dirac distribution. v. Find the difference in temperature between items ii and iv above and express this difference as percentage.arrow_forwardThe figure below is a part of the energy band diagram of a P-type semiconductor bar under equilibrium conditions (i.e., EF is constant). The valence band edge is sloped because doping is nonuniform along the bar. Assume that Ev rises with a slope of ∆ ⁄ L .arrow_forward
- For Ge semiconductor, assume the Fermi energy level is 0.15 eV below the conduction band energy Ec. Let the absolute temperature T for items i and ii be 200 K. i. Find the number of quantum states between Ec and Ec + 5 x KbT. ii. Determine the probability of a state being empty of an electron at Ec + 5 x KbT. iii. Find the temperature at which there is an electron at the state Ec + 0.5 x KbT with probability 30%. iv. Repeat item iii by using the Boltzmann approximation rather than the Fermi-Dirac distribution. v. Find the difference in temperature between items iii and iv above and express this difference as percentage.arrow_forwardDescribe the difference in band structure between an insulator and a semiconductor. (Explain with diagram) In an insulator the band gap is relatively wide so that, at room temperature, electrons do not have sufficient energy to cross it. There are therefore no electrons in the conduction band. In a semiconductor the band gap is sufficiently narrow for electrons to be able to cross it at room temperatures. The conduction band therefore contains some electrons.arrow_forwardB2arrow_forward
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