Question

Underline all the correct answers. Explain why an answer is correct or why it is wrong. You are supposed to select all of the correct answers (1-6) for each roman numeral (I-III)

--Please justify/explain answers thoroughly--

Problem 2. If a Si Wafer is at 300K, the valence and conduction band are

(I)

1-      Both are completely empty

2-      Both are completely filled.

3-      Both are partially empty.

4-      Both are partially filled.

5-      None of the above

6-      All of the above 1-4.

(II)

1-      CB band is completely empty and VB is completely filled.

2-      VB band is completely empty and CB is completely filled.

3-      CB band is partially empty and VB is completely filled.

4-      VB band is partially empty and CB is completely filled.

5-      None of the above

6-      All of the above (1-4)

(III)

1-      CB band is partially filled and VB is completely filled.

2-      VB band is partially filled and CB is completely filled.

3-      CB band is partially empty and VB is partially filled.

4-      VB band is partially empty and CB is partially filled.

5-      None of the above

6-      All of the above (1-4)

Answer 1

(I) Correct Option is (3 ,4 ) - Both are partially empty. or Both are partially filled.

When an electron/hole is in valence band, it means these are still attached to Si atom trough a covalent bond. When the temperature is increased, some of these electrons/holes gain energy and breaks the covalent bond, further move away to the conduction band.

During increasing temperature, some of the electrons/holes gain the energy and move to the conduction band. So the Both valence and conduction band are partially filled with electrons/holes or in other words, both valence and conduction band are partially empty.

(I) Correct Option is (5) - None of the above

(I) Correct Option is ( 3,4 ) - CB band is partially empty and VB is partially filled.

VB band is partially empty and CB is partially filled.