Electronics - Semiconductor Principles

Exercise :: Semiconductor Principles - General Questions

11. 

In "p" type material, minority carriers would be:

A. holes
B. dopants
C. slower
D. electrons

Answer: Option D

Explanation:

The purpose of p-type doping is to create an abundance of holes. In the case of silicon, a trivalent atom (typically from Group 13 of the periodic table, such as boron or aluminium) is substituted into the crystal lattice. The result is that one electron is missing from one of the four covalent bonds normal for the silicon lattice. Thus the dopant atom can accept an electron from a neighboring atom's covalent bond to complete the fourth bond. This is why such dopants are called acceptors. The dopant atom accepts an electron, causing the loss of half of one bond from the neighboring atom and resulting in the formation of a "hole". Each hole is associated with a nearby negatively charged dopant ion, and the semiconductor remains electrically neutral as a whole. However, once each hole has wandered away into the lattice, one proton in the atom at the hole's location will be "exposed" and no longer cancelled by an electron. This atom will have 3 electrons and 1 hole surrounding a particular nucleus with 4 protons. For this reason a hole behaves as a positive charge. When a sufficiently large number of acceptor atoms are added, the holes greatly outnumber thermal excited electrons. Thus, holes are the majority carriers, while electrons become minority carriers in p-type materials.

12. 

What can a semiconductor sense?

A. magnetism
B. temperature
C. pressure
D. all of the above

Answer: Option D

Explanation:

No answer description available for this question. Let us discuss.

13. 

When an electron jumps from the valence shell to the conduction band, it leaves a gap. What is this gap called?

A. energy gap
B. hole
C. electron-hole pair
D. recombination

Answer: Option B

Explanation:

No answer description available for this question. Let us discuss.

14. 

Forward bias of a silicon P-N junction will produce a barrier voltage of approximately how many volts?

A. 0.2
B. 0.3
C. 0.7
D. 0.8

Answer: Option C

Explanation:

No answer description available for this question. Let us discuss.

15. 

Which semiconductor material is made from coal ash?

A. germanium
B. silicon
C. tin
D. carbon

Answer: Option A

Explanation:

No answer description available for this question. Let us discuss.