Semiconductors and Their Concept

A semiconductor is a silicon-based material that conducts electricity better than an insulator, such as glass, but not as well as a pure conductor, such as copper or aluminium. Semiconductors, also known as chips or semis, are found in a wide range of products, including computers, smartphones, appliances, gaming hardware, and medical devices. In terms of electrical conductivity, semiconductors are crystalline solids that fall somewhere between a conductor and an insulator. The energy gap between the valence and conduction bands in semiconductors is very small. Electrons can jump from the conduction band to the valence band in conductors. We know that N-type and p-type semiconductors are the two main types of semiconductors. Most charge carriers in an N-type semiconductor are free electrons, while holes are in the minority. Most charge carriers in a P-type semiconductor are holes, while free electrons are in the minority.

Products of Semiconductors

ICs(integrated circuits) and discrete electronic components like diodes and transistors are products of semiconductors. Common elemental semiconductors are silicon and germanium. Silicon is well-known for those. Silicon forms most of the integrated circuits. Common semiconductor compounds are gallium arsenide or indium antimonide. Semiconductors became essential for several electronic appliances and social infrastructure that supports our lifestyle. Semiconductors play a crucial role in equipment control in a field, like operating air conditioners at a snug temperature, improving automobile safety and laser treatment. Moreover, the advances in semiconductor technology have driven systems efficiency, miniaturisation, and energy savings, which help preserve the world environment and achieve a safe and comfy life and form a prosperous future.

Intrinsic semiconductor

The amount of holes and electrons in a material is thus determined by its properties rather than contaminants. They’re also known as undoped semiconductors or i-type semiconductors. Silicon and germanium are examples of I-type semiconductors. These elements have atomic numbers of 14 and 32, respectively, and they are members of the IVth Group of the periodic table.

Extrinsic semiconductors

The bandgap in extrinsic semiconductors is controlled by intentionally adding small impurities to the fabric. This process is termed as doping. By using an appropriate impurity, the conductivity of a semiconductor can be increased several times. Extrinsic semiconductors are those that result from the addition of an impurity to a pure semiconductor. These dopants are chosen based on the goal we want to achieve with the given extrinsic semiconductor. To make an honest extrinsic semiconductor, only a small amount of dopant is required. However, we must ensure that the dimensions of the dopant atom are nearly identical to the scale of the initial atom when selecting the dopant.

N-type and P-type semiconductors 

N-type: An extrinsic semiconductor is created by doping pentavalent elements into a pure semiconductor such as Si or Ge.

When a pentavalent atom is added to a pure semiconductor, four electrons of the Si atom form a covalent bond with the four electrons of the dopant. The pentavalent impurity of the fifth electron, on the other hand, is only weakly linked to the parent atom. As a result, the atom’s electron will be free to wander around the lattice even at very low ionisation energy. As a result, even at room temperature, this electron can traverse the lattice. After doping at room temperature, the ionisation energy of the silicon crystal lattice drops to 0.05eV. On the other hand, an intrinsic semiconductor has a similar ionisation energy of around 1.1eV. Moving an electron from the valence band to the conduction band becomes easier. The number of electrons is unaffected by the ambient temperature. However, the number of electrons generated by a dopant atom varies depending on the semiconductor’s doping level.

P-type: A semiconductor device is an extrinsic semiconductor created by doping a pure semiconductor with a trivalent element, such as Si or Ge. Three of the electrons of a trivalent dopant atom form covalent bonds with three neighbouring Si atoms when it replaces a -Si atom in an intrinsic semiconductor. However, an electron in the Si atom remains unbonded due to this process. Because there is no electron to bond with the fourth Si atom, the trivalent dopant and the fourth silicon atom form a hole or vacancy. The electron from the lattice may jump in to fill the void within the Si lattice, leaving a void at its original location. Conduction can now take place through this hole.

Conclusion 

Extrinsic semiconductors are formed when a pure or intrinsic semiconductor is doped with specific impurities. Depending on whether a trivalent or pentavalent dopant is used, extrinsic semiconductors can be p-type or n-type. In a p-type semiconductor, holes make up the majority of charge carriers. In n-type semiconductors, electrons make up the majority of charge carriers. As a result, doping will not affect total neutrality. As a result, the total electric charge of an extrinsic semiconductor is zero.