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Which of the following correctly orders the band gap energies of Silicon (Si), Germanium (Ge), and Diamond (C) at room temperature?
E(Ge) < E(Si) < E(C)
E(Si) < E(Ge) < E(C)
E(C) < E(Si) < E(Ge)
E(Ge) < E(C) < E(Si)
E(Ge) < E(Si) < E(C)
The band gap energy (EgтАЛ) of a material is the energy difference between the top of the valence band and the bottom of the conduction band. At room temperature, Germanium has the smallest band gap (~0.67 eV), followed by Silicon (~1.12 eV), and Diamond has the largest (~5.47 eV).
The band gap energy (EgтАЛ) of a material is the energy difference between the top of the valence band and the bottom of the conduction band. At room temperature, Germanium has the smallest band gap (~0.67 eV), followed by Silicon (~1.12 eV), and Diamond has the largest (~5.47 eV).
EgтАЛ(Ge)тЙИ0.67eV
EgтАЛ(Si)тЙИ1.12eV
EgтАЛ(C)тЙИ5.47eV
The band gap magnitude depends on the strength of atomic bonding and lattice constant. Carbon atoms in diamond form very strong covalent bonds, resulting in a large band gap characteristic of an insulator. Silicon and Germanium, located below carbon in the periodic table, have weaker interatomic bonds, leading to smaller band gaps that categorize them as semiconductors.
Materials with EgтАЛ<3eV are generally classified as semiconductors.
Diamond is a wide band gap material (>5eV), making it a natural electrical insulator.
The band gap of semiconductors decreases slightly as temperature increases.
Small band gap semiconductors allow easy control of charge carriers for electronic switching.
Wide band gap materials like diamond are excellent for high-power and high-frequency applications due to thermal stability.
Low band gap materials are susceptible to thermal noise at high temperatures.
Large band gap materials require high voltages for electron excitation.
Silicon: Integrated circuits and solar cells.
Germanium: Infrared optics and early transistor technology.
Diamond: High-power electronics and heat sinks.
The energy values are taken at 300K.
Option B is incorrect because silicon has a larger band gap than germanium.
Option C is incorrect as it presents the order in reverse.
Option D is incorrect due to the misplacement of the Si value.
A is correct тАФ The band gap energy increases in the order E(Ge)<E(Si)<E(C).
Remember the sequence 'Ge-Si-C' for increasing band gaps; this is a common trap in questions involving semiconductor device physics.
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