1- Element semiconductors are located in the fourth column of the periodic table of elements, what does make these elements different from other elements?

2- What is the difference between valence electrons in an atom with other electrons?

3- What is the difference between conducting material, semiconductors, and insulators based on their bandgap energy?

4- Compare the bandgap energy between Si and Ge. Why Si has a larger bandgap energy?

5- What is the definition of unit cell in a lattice?

6- What is the difference between a direct bandgap semiconductor and an indirect bandgap semiconductor and provide a few example for each.

7- An orange light emitting diode emits green light in low temperatures, why?

8- What is Fermi Distribution and how does it change with temperature?

9- What are Nc and Nv? And what do they show?

10- What is polysilicon?

11- What is complete ionization? How much energy is required to ionize "B" and "As" in Silicon?

12- Explain what happens when n-type impurities are added to Si.

13- What is the difference between intrinsic and extrinsic semiconductors?

14- Explain the following Figure:

15- Explain the following Figure:

16- In a diamond crystal, the lattice constant, a, is 0.356 nm, what is its atomic density (number of atoms per cm^-3)?

17- In a diamond crystal, the lattice constant is 0.356 nm, what is the minimum distance between the atoms?

18- Find the density of electrons and holes in Si if the density of n-type impurity is 1.5ni and the density of p-type impurity is 1.2ni, where ni is the intrinsic density of carriers in Si at T=500K (Hint use Fig. 1.18).

19- Is the semiconductor in question 18 a degenerate semiconductor or a non-degenerate semiconductor?

20- Show eV is an energy unit.

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