Virtual Labs

What does the density of states (DOS) represent in a semiconductor?

a: The number of free electrons Explanation

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b: The number of available energy states per unit volume per unit energy Explanation

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c: The total energy stored in the system Explanation

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d: The number of holes present in the conduction band Explanation

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At absolute zero (0 K), what is the probability that an energy state below the Fermi level is occupied?

a: 0 Explanation

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b: 0.5 Explanation

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c: 1 Explanation

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d: Cannot be determined Explanation

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What does the Fermi-Dirac distribution function f(E) calculate?

a: Density of holes Explanation

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b: Probability of a state being occupied by an electron Explanation

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c: The drift velocity of electrons Explanation

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d: Energy band gap of a semiconductor Explanation

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What happens to the Fermi-Dirac distribution at very high energies (E >> E_F) and room temperature?

a: It approaches 1 Explanation

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b: It becomes negative Explanation

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c: It becomes zero Explanation

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d: It approaches zero Explanation

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For conduction band electrons in a 3D semiconductor, how does the DOS vary with energy?

a: Linearly with energy Explanation

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b: Inversely proportional to energy Explanation

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c: Proportional to the square root of energy Explanation

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d: Constant with energy Explanation

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Why is the Fermi level significant in determining electrical properties of semiconductors?

a: It determines the resistivity only Explanation

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b: It defines where electrons are always present Explanation

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c: It determines carrier concentration through occupation probability Explanation

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d: It determines the bandgap energy Explanation

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In intrinsic silicon at T = 300 K, where is the Fermi level located?

a: At the bottom of the conduction band Explanation

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b: At the top of the valence band Explanation

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c: Exactly at the midpoint of the bandgap Explanation

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d: Slightly below the conduction band Explanation

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Which of the following affects the density of states near the conduction band edge?

a: Effective mass of electrons Explanation

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b: Energy gap width Explanation

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c: Fermi level Explanation

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d: Mobility of carriers Explanation

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How does increasing temperature affect the sharpness of the Fermi-Dirac distribution?

a: It makes it sharper Explanation

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b: It makes it more step-like Explanation

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c: It spreads it out over energy Explanation

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d: No effect Explanation

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Density of States