Semiconductors are a vital electronic component of modern technology, used to make everything from smartphones and laptops to solar panels and electric cars. At their most basic level, semiconductors are materials that can conduct electricity, but not in the same way as metals.
To understand how semiconductors conduct electricity, it is first necessary to understand the basic structure of these materials. Semiconductors are usually made of nonmetals such as silicon or germanium, which have four valence electrons in their outermost shell. These electrons are responsible for forming bonds with neighboring atoms, forming a crystalline lattice structure.
The Basics of Semiconductor Structure
Semiconductors are substances that can conduct electricity, but not like metals. which have four valence electrons in their outermost shell. These electrons form covalent bonds with neighboring atoms, forming a crystalline lattice structure.
At very low temperatures, these atoms are tightly bound together, and there are no free electrons available to conduct electricity. However, as the temperature increases, some electrons in the lattice gain sufficient energy to break free from their bonds and become “free electrons”.
Holes and Dopants
What makes semiconductors unique is the presence of “holes” in the lattice structure. These holes are regions where an electron is missing, and they move through the lattice structure and act like positive charges, allowing them to conduct electricity.
Additionally, we intentionally add impurities, or “dopants,” to semiconductor materials to create regions with an excess of electrons or an excess of holes.
Types of Semiconductors
Impurities combine with an extra electron, creating “n-type” semiconductors, where more free electrons are available to conduct electricity. Conversely, if impurities with a missing electron are added, we create a “p-type” semiconductor, where more holes are available to conduct electricity.
1. Intrinsic Semiconductors
These are pure semiconductors made up of a single type of atom, such as silicon (Si) or germanium (Ge). Intrinsic semiconductors have perfectly balanced numbers of electrons and holes, and they have no net electric charge. However, they still conduct electricity due to the movement of electrons and holes.
2. Extrinsic Semiconductors
These are also semiconductors that are doped with impurities to change their electrical properties. There are two types of extrinsic semiconductors:
(i) N-type Semiconductors
These semiconductors are doped with impurities that have more valence electrons than atoms in the semiconductor material, such as phosphorus (P) or arsenic (As). These extra electrons are able to move through the material and create a surplus of a negative charge, giving the material an overall negative charge.
(ii) P-type Semiconductors
These semiconductors are also doped with impurities that have fewer valence electrons than atoms in boron (B) or aluminum (Al). These impurities create “holes” in the semiconductor’s valence band, which accept electrons and create a surplus of positive charge, giving the material an overall positive charge.
10 examples of semiconductors
- Silicon (Si)
- Germanium (Ge)
- Gallium Arsenide (GaAs)
- Indium Phosphide (InP)
- Silicon Carbide (SiC)
- Gallium Nitride (GaN)
- Zinc Oxide (ZnO)
- Cadmium Sulfide (CdS)
- Cadmium Telluride (CdTe)
- Copper Indium Gallium Selenide (CIGS)
Why are semiconductors used in electronics?
This is used in electronics because of its unique electrical properties. Semiconductors have electrical conductivity between that of a conductor and an insulator, which makes them ideal for controlling the flow of electric current in electronic devices. Some of the reasons for using semiconductors in electronics are as follows.
1. Controllability
These are manipulated to have specific electrical properties, such as resistance or conductivity, by adding impurities or changing their structure. It is the precise control of the flow of electric current in an electronic circuit.
2. Miniaturization
The small size and low weight of semiconductors make them ideal for use in electronic devices that require miniaturization and portability. It is of particular use for devices such as smartphones, laptops and other portable electronics.
3. Efficiency
These are highly efficient at converting electrical energy into light or other forms of energy. This makes them ideal for use in LEDs, solar cells, and other energy-efficient devices.
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