Question 13 4 pts Which of the following is true about silicon? Select all that

Question

Question 13 4 pts Which of the following is true about silicon? Select all that apply. When doped with an element from Group Ill on the periodic table, it becomes a P-type material The doping of silicon with Group IV elements results in free charge carriers in the semiconductor. In doped silicon, conventional current and electron current flow in the opposite directions. Common doping elements to create an P-type material would be boron and indium. O In a P-type material, the term 'holes' refers to voids in the silicon crystal structure where atoms are intentionally missing.

Explanation / Answer

1. As per older convention, group III of periodic table contain Boron, Alumiium, Gallium, Indium etc. When silicon is doped with Boron or gallium, outer shell of doping material has 3 electrons and it catches one electron from silicon. This creates a hole in valence band of silicon. This type of resultant material is called P type material. Thus doping of silicon with Group III element (Boron or galium) produces P type material. Statement is correct.

2. Doping of silicon with Phosphorus (GROUP 15) produces free electron. Similarly doping with boron, gallium as explained above produces free charge carrier in the form of holes. But doping with group IV does not produce any free charge carrier. Statement is incorrect.

3. Like in any other circuit, conventional current flows in the direction opposite to electron flow. In doped silicon, electri current flows due to movement of both holes and free electrons. However, electron flow is always oppsite to direction of conventional current (which is in the direction of holes). Therefore, electron current also flows in sme direction as conventional current flow. Statement is Incorrect. (Dear student, kindly note that, question asks about electron current flow. Not electron flow. Electron flow is in direction oppositr to conventional current flow. But current due to electron flow is same direction. If you have query, kindly ask me).

4. As explained in part 1, doping with Boron or gallium produces P type material. Same is achieved by doping with Indium which is also a Group III elelmet. Hence statement is correct.

5. As explained in Part 1 & 2, doping with boron produces P type material. In P type material, outer shell of doping material has 3 electrons and it catches one electron from silicon. This creates a hole in valence band of silicon. A hole is defined as the absence of an electron in a particular place in an atom. Therefore statement is incorrect as it states that hole refers to voids where atoms are missing.  

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