Virtual Labs

1. What is the density of states (DOS) in a system?

a: Number of particles per unit volume Explanation

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b: Quantum mechanical wave function distribution Explanation

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c: Number of allowed modes or states per unit energy Explanation

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d: Energy distribution across conduction bands Explanation

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2. Which of the following is true about the Fermi level

a: The Fermi level represents the highest occupied energy level at absolute zero. Explanation

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b: The Fermi level is the energy level which has a Fermi probability for intrinsic silicon as 50%. Explanation

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c: The Fermi level changes with temperature. Explanation

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d: The Fermi level will decrease when electrons are added to the system. Explanation

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e: Both a and b Explanation

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3. What is the effective mass of an electron in a material?

a: The actual mass of an electron in free space. Explanation

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b: The mass of an electron when it reaches the conduction band. Explanation

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c: The mass of an electron when f(E)=1/2 Explanation

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d: A modified mass that accounts for the interaction of an electron with the periodic crystal lattice. Explanation

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4. How does DOS(Density of States) vary with energy in intrinsic material?

a: DOS is constant Explanation

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b: DOS in conduction band increases with energy Explanation

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c: DOS in conduction band decreases linearly with energy Explanation

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d: None of the above Explanation

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5. How can you calculate the carrier concentration in the conduction band of a semiconductor?

a: Integrate DOS between Ev and Ec Explanation

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b: Integrate DOS between Ev and Ec after adding the Fermi function Explanation

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c: Multiply DOS with f(E) and Integrate DOS for all E below Ev Explanation

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d: Muliply DOS with f(E) and integrate DOS for all E above Ec Explanation

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