Question

When you add a controlled amount of substance known as an impurity to a pure semiconductor, its conductivity increases. This process is known as doping. The addition of an impurity can increase or decrease the number of available electrons. If the number of electrons is increased, the extra electrons conduct electricity. If the number of electrons is decreased, a vacant hole is created. The adjacent electron enters the vacant hole and conducts electricity. Thus, it seems like the holes act as charge carriers. They are considered to be positive charge carriers. Depending upon the charge carriers that conduct electricity, there are two types of semiconductors: p-type semiconductors and n-type semiconductors.Which of the following statements are correct with respect to semiconductors?

a) The addition of group 3A elements to group 4A semiconductors decreases the conductivity of the group 4A semiconductors.
b) The conductivity of semiconductors can be increased by the doping process.
c) As the temperature increases, the conductivity of semiconductors decreases.
d) The addition of group 5A elements to group 4A semiconductors increases the conductivity of the group 4A semiconductors.
e) Holes are charge carriers in p-type semiconductors.
f) Electrons are charge carriers in n-type semiconductors.

Answer 1

In the context of semiconductors, doping with group 5A elements increases conductivity by creating n-type semiconductors. Group 3A elements also increase conductivity but generate p-type semiconductors by creating holes. Conductivity generally increases with temperature. So the correct option is b,d,e, and f.

Step-by-step explanation:

When looking at the properties of semiconductors and the process of doping, it's essential to understand how different impurities affect their conductivity. To address the student's question on the effects of doping in semiconductors:

• Statement b) is correct; the conductivity of semiconductors can indeed be increased by the doping process.
• Statement d) is correct; adding group 5A elements to group 4A semiconductors typically increases their conductivity because those elements have more valence electrons, which become free to conduct electricity as extra electrons or 'n-type' carriers.
• Statement e) is correct; holes are charge carriers in p-type semiconductors.
• Statement f) is correct; electrons are charge carriers in n-type semiconductors.

However, statement a) is incorrect because the addition of group 3A elements, which have fewer valence electrons than group 4A elements, creates p-type semiconductors, which increase the conductivity by creating holes that act as positive charge carriers. Lastly, statement c) is incorrect; the conductivity of semiconductors typically increases with temperature because higher temperatures provide energy to bridge the energy gap between valence and conduction bands, creating more charge carriers.

Answer 2

See explaination

Step-by-step explanation:

1. The addition of group 3A elements to group 4A semiconductors decreases the conductivity of the group 4A semiconductors: Wrong

The addition of 3A group elements inreases the conductivity and make them extrinsic semiconductors( p-type)

2. The conductivity of semiconductors can be increased by the doping process.: Correct

3.As the temperature increases, the conductivity of semiconductors decreases.. wrong

As the temperature increases, the conductivity of semiconductors increases.

4. The addition of group 5A elements to group 4A semiconductors increases the conductivity of the group 4A semiconductors: Correct : They will create n-type semicoductor.

5.Holes are charge carriers in p-type semiconductors: Correct

6. Electrons are charge carriers in n-type semiconductors: Correct