Underline all the correct answers. Explain why an answer is correct or why it is
ID: 2267294 • Letter: U
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)
Explanation / Answer
(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.
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