Question

When a P-type semi-conductor is heated: (A) number of holes increases while that of electrons decreases (B) number of electron increases while that of hole decreases (C) number of electrons and holes remains same (D) number of electrons and holes increases equally

Short answer

The correct answer is (D): the number of electrons and holes increases equally when a P-type semiconductor is heated, maintaining the overall balance between the majority and minority charge carriers while accounting for the effect of heating on the material.

Step-by-step solution

Understand the P-type Semiconductor

A P-type semiconductor is characterized by the presence of more holes (positively charged) compared to free electrons (negatively charged). This is because it is doped with an impurity that has one less electron than the host material.

Effect of Heating on P-type Semiconductors

When any semiconductor is heated, the thermal energy causes the creation of more electron-hole pairs. In other words, the number of free electrons and holes will increase due to the extra energy. However, in a P-type semiconductor, holes are the majority charge carriers, while free electrons are minority charge carriers.

Evaluate the Options

(A) - If only the number of holes increases and the number of electrons decreases, it would mean that the heating results in an imbalance between the majority and minority carriers. This is not the case, as both numbers should increase. (B) - This option suggests that the number of electrons increases while the number of holes decreases, which implies that the material becomes balanced or even N-type. This is not accurate, as heating should generate more electron-hole pairs, not change the type of material. (C) - This option states that the number of electrons and holes remains the same upon heating, which is incorrect because heating should cause the generation of more electron-hole pairs. (D) - This option correctly states that the number of electrons and holes will increase equally upon heating. This maintains the overall balance between the majority and minority charge carriers while accounting for the effect of heating on the material. Therefore, the correct answer is (D): the number of electrons and holes increases equally when a P-type semiconductor is heated.

Key concepts

Electron-Hole Pairs

In semiconductor physics, electron-hole pairs are fundamental. They represent a relationship between electrons, which are negatively charged, and holes, which are positively charged.
When an electron in a semiconductor gets enough energy (from, let's say, heating), it can move from the valence band to the conduction band. This movement leaves behind an absence, known as a 'hole.'
It's like when someone leaves their seat at a concert, and now there's an empty spot. This seat, or hole, can then "move" when another electron jumps to fill the place. Hence, we talk about electron-hole pairs because their movement is interlinked.

• Electron-hole pairs form due to energy input.
• They are crucial in conductivity and the behavior of semiconductors.

The creation of these pairs explains why semiconductors are such interesting materials. They can have controlled conductive properties by how many of these pairs exist.

Effect of Heating

When you heat a P-type semiconductor, you're adding energy to it.
This energy allows electrons to jump up to higher energy levels, creating more electron-hole pairs. You can think of heating like giving more fuel to a tiny engine, making it run faster.
The effect of heating generally increases the number of both electrons and holes in the material.

• Heating generates new electron-hole pairs.


• It affects both types of charge carriers in a semiconductor.

By increasing the temperature, the material becomes more conductive, since more charge carriers are available to move and carry electrical current.

Majority and Minority Carriers

In P-type semiconductors, holes are the majority charge carriers.
This means there are more holes than electrons, which is due to the way P-type semiconductors are constructed. Doping a material with an element that has fewer electrons than the host creates these extra holes.
Electrons, on the other hand, are minority carriers in a P-type material as they are less in number.

• Holes dominate a P-type semiconductor and dictate its electrical properties.
• Electrons play a lesser role, but they are still vital to consider.

Understanding the balance between majority and minority carriers is key when predicting how semiconductors will behave under different conditions.

Semiconductor Physics

Semiconductor physics explores the unique properties of semiconductors, which are materials that aren't exactly conductors, but aren't insulators either.
This intermediate state allows them to be engineered to exhibit a wide range of electrical properties.
The capabilities of semiconductors are enhanced using "doping," which involves adding small quantities of an element to change behavior of charge carriers inside.

• Semiconductors have versatile electrical properties.
• Doping and conditions like temperature can significantly alter these properties.

Mastering the physics of semiconductors can lead to the development of advanced technologies, including microchips and sensors that capitalize on these flexible materials.