Invention Of Semiconductor And Its Impact On Our Life

The invention of semiconductors in the 1950s marked a major turning point in the field of electronics, leading to rapid growth and development in the industry. Semiconductors, such as silicon, are used to create transistors and integrated circuits, which allow for the development of smaller, faster and more efficient electronic devices.

One of the most significant advancements was the creation of the microprocessor, a tiny chip that contains all the components needed to process data. This led to the development of personal computers and increased availability of computing power for personal and professional use. Semiconductors also play a key role in the development of other electronic devices, such as smartphones, tablets, and televisions, making them smaller, more powerful and widely available.

The role of semiconductors is important in quantum physics, the Mangalyaan and the Chandrayaan. The invention of semiconductors has also led to the development of new technologies such as solar cells and LED lights, revolutionizing the energy industry. These energy-efficient devices have replaced traditional devices such as incandescent bulbs and CRT televisions, which were known to waste energy and produce heat.

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Semiconductor And Its Types

A semiconductor is a material that has electrical conductivity between that of a conductor (generally metals) and an insulator (such as ceramics). It is used in a wide range of electronic devices such as transistors, diodes, and integrated circuits.

Some of the most widely used semiconductors include gallium arsenide, germanium, and silicon. These materials have unique electronic properties that make them suitable for different applications. For example, silicon is commonly used in electronic circuit fabrication because of its low cost and wide availability, while gallium arsenide is used in high-performance applications such as solar cells, laser diodes, and microwave devices because of its high electron mobility. Germanium is also used in electronic applications but it is not as widely used as silicon.

There are two main types of semiconductors:

• Intrinsic semiconductors

• Extrinsic semiconductors

Intrinsic Semiconductor

Intrinsic semiconductors are pure materials that have no impurities. The most common types of intrinsic semiconductors are silicon and germanium, which belong to group 4 of the periodic table. They have four valence electrons and are responsible for the material's conductive properties. At absolute zero temperature, intrinsic semiconductors act as insulators, but at room temperature, thermal energy may cause some of the covalent bonds to break, generating free electrons. These electrons move into the conduction band, leaving behind holes in the valence band. These intrinsic charge carriers are responsible for the conductive properties of intrinsic semiconductor materials.

In an intrinsic semiconductor, the number of holes, n_h and the number of free electrons, n_e are equal.

i.e. n_e= n_h= n_i

Where n_i = intrinsic carrier concentration

These holes move in the direction of negative potential when an electric field is applied, producing the hole current I_h.

The electron current Ie and the hole current Ih are added to create the overall current, I.

i. e. I = I_e + I_h

Extrinsic Semiconductor

When small amounts of impurities, such as boron or phosphorus, are added to pure semiconductors, like silicon or germanium, the electrical conductivity of the material increases. This process is called doping and the resulting material is known as an extrinsic semiconductor. The impurities added are called dopants, and they can be of two types: p-type dopants, which create a deficiency of electrons known as holes, and n-type dopants, which create an excess of electrons.

Doping

It is the process of introducing impurities, called dopants, into a semiconductor material in order to change its electrical properties. In the preparation of extrinsic semiconductors, the amount of dopant atoms added must be carefully controlled, typically one dopant atom for every 108 atoms of the semiconductor.

The dopants can increase the number of holes or electrons in the material, making it more conductive. For example, by adding a pentavalent impurity with five valence electrons to a pure semiconductor, the number of electrons in the material will increase. Based on the type of dopant added, extrinsic semiconductors can be classified into two types: N-type, created by adding impurities with an extra electron, and P-type, created by adding impurities with one less electron.

Types Of Extrinsic Semiconductor

• p-type semiconductor

• n-type semiconductor

P-type

Each of the four valence electrons in a pure (intrinsic) Si or Ge semiconductor is used to create four covalent bonds with its neighbours (see figure below). The nucleus and non-valent electrons that make up each ionic core have a net charge of +4 and are surrounded by 4 valence electrons. Since neither more electrons nor holes exist In this instance, there will always be an equal number of electrons and holes present.

Now, if an element having three valence electrons, such as a Group 3 element like Boron (B) or Gallium (Ga), were to replace one of the atoms in the semiconductor lattice, the electron-hole balance would be changed. Only three valence electrons can be contributed to the lattice by this impurity, leaving one extra hole (see figure below). An acceptor is another name for a Group 3 impurity because holes will "accept" free electrons

A semiconductor that has been doped with an acceptor is referred to as a p-type semiconductor; "p" stands for positive. This is because an acceptor contributes extra holes, which are thought to be positively charged. Keep in mind that the substance itself continues to be electrically neutral. In a p-type semiconductor, the holes, which outnumber the free electrons, carry the majority of the current. The majority carriers in this situation are holes, while the minority carriers are electrons.

N-type

In addition to substituting a lattice atom with a group 3 element, an impurity atom with five valence electrons from group 5, such as arsenic or phosphorus, can also be added to the lattice. In this case, the impurity atom donates an extra electron to the lattice, which can only hold four valence electrons. This results in an excess of electrons in the material, known as n-type semiconductor, but the material remains electrically neutral. The impurity atom that donates an electron is known as a donor impurity.

A semiconductor that has been doped with a donor is referred to as an n-type semiconductor; "n" stands for negative. Donor impurities contribute negatively charged electrons to the lattice. In an n-type material, free electrons outnumber holes, making electrons the majority carrier and holes the minority carrier.

Impact Of Semiconductors On Modern Life

The invention of the semiconductor has had a profound impact on modern society, revolutionising the way we live and work. Some of the ways in which life has been changed by the invention of the semiconductor include:

• Computing: The development of the microprocessor, which is a tiny chip that contains all of the components needed to process data, made it possible for the creation of personal computers and the widespread availability of computing power for personal and professional use.

• Communication: Semiconductors have played a key role in the development of electronic devices such as smartphones, tablets, and laptops, which have revolutionised the way we communicate and access information.

• Entertainment: The use of semiconductors in televisions, gaming consoles and other electronic devices has led to the creation of high-definition displays and improved graphics, greatly enhancing the entertainment experience.

• Transportation: Semiconductors have enabled the creation of advanced navigation and control systems in cars and aeroplanes, making transportation safer and more efficient.

• Healthcare: Semiconductors have played a crucial role in the development of medical imaging devices such as CT scanners and MRI machines, allowing for earlier and more accurate diagnoses of diseases.

• Energy: Semiconductors have enabled the development of new technologies such as solar cells and LED lights, which have revolutionised the energy industry and helped to reduce energy consumption.

• Industry: Semiconductors have enabled the automation of many industrial processes, leading to increased efficiency and productivity.

• Space exploration: Semiconductors have enabled the development of advanced technologies such as spacecraft and satellites, enabling space exploration and the collection of valuable data about the Earth and the universe.

Overall, the invention of the semiconductor has had a transformative effect on nearly every aspect of modern life, making it more convenient, efficient, and connected.

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