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Select the correct option for the band gap energies of Ge, Si and GaAs. Where E(Ge) = band gap energy of Ge, E(Si) = band gap energy of Si and E(GaAs) = band gap energy of GaAs
E(GaAs) > E (Si) > E (Ge)
E(Ge) > E (GaAs) > E (Si)
E(GaAs) > E (Ge) > E (Si)
E(Ge) > E (Si) > E (GaAs)
E(GaAs) > E (Si) > E (Ge)
The band gap energy (EgтАЛ) of a semiconductor represents the energy difference between the valence band and the conduction band. The standard values are approximately 0.67┬аeV for Germanium (Ge), 1.12┬аeV for Silicon (Si), and 1.42┬аeV for Gallium Arsenide (GaAs), confirming that E(Ga┬аAs)>E(Si)>E(Ge).
The band gap energy (EgтАЛ) of a semiconductor represents the energy difference between the valence band and the conduction band. The standard values are approximately 0.67┬аeV for Germanium (Ge), 1.12┬аeV for Silicon (Si), and 1.42┬аeV for Gallium Arsenide (GaAs), confirming that E(Ga┬аAs)>E(Si)>E(Ge).
Think of the band gap as a 'hump' an electron must jump over to reach the other side. GaAs has the highest 'hump' (most energy required), while Ge has the lowest, making it easier for electrons to jump with less thermal excitation.
G-S-G: Ge (0.6) < Si (1.1) < GaAs (1.4); think 'Getting Smaller' energy as you go from GaAs to Ge.
EgтАЛ=EcтАЛтИТEvтАЛ тАФ Energy gap difference between conduction and valence band minima/maxima
E=╬╗hcтАЛ тАФ Relation between photon energy and wavelength for band gap excitation
Semiconductors are classified by their band gap, which determines the minimum energy required to promote an electron from the valence band to the conduction band. As we move down the periodic table within the same group or change material composition, the atomic size and bonding characteristics change, affecting the strength of the crystalline lattice and consequently the EgтАЛ. GaAs, being a compound semiconductor, generally exhibits a wider band gap than common elemental semiconductors like Si and Ge due to the nature of its ionic-covalent bonding.
Band gap energy is temperature-dependent, usually decreasing slightly as temperature increases.
Ge is a narrow band gap semiconductor, while GaAs is a wide band gap semiconductor.
Si is the most widely used industrial semiconductor due to its moderate band gap and the natural occurrence of SiO2тАЛ.
GaAs allows for high-speed electronics and optoelectronic devices due to its band structure.
Si provides excellent thermal stability and ease of fabrication.
Ge is highly sensitive to temperature, leading to high leakage current at room temperature.
GaAs is used in high-frequency microwave circuits and LEDs.
Si is the foundation of modern integrated circuits and solar cells.
Values at 300 K: Ge (0.67 eV), Si (1.12 eV), GaAs (1.42 eV).
Option B, C, and D are incorrect because they fail to follow the ascending order of atomic-bond energy potential.
A is correct тАФ The band gap energies are in the order E(Ga┬аAs)>E(Si)>E(Ge) based on their respective electronic band structures.
Always memorize the specific band gap values of Si and Ge, as they are frequently tested constants in Physics and Electronics engineering papers.
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