Basics of Semiconductor – Doping

A semiconductor is a material from which the current flows easily. Semiconductors are solid-state materials that produce or transmit an electric current when a voltage is applied. They are essential to modern technology and are the foundation for much of the electronic equipment we use in our daily lives. Semiconductor devices make use of various combinations of silicon and germanium in their making.

Basic Concepts of a Semiconductor

The semiconductor is a crystalline compound used to manufacture integrated circuits and other electronic devices. Semiconductors are the materials of the active parts of transistors, light-emitting diodes, solar cells, and lasers. Electrons and holes are responsible for carrying charges in a semiconductor. The electrons play the role of majority carriers, and the holes play the role of minority carriers. The impurities are introduced using either ion implantation or diffusion doping. Semiconductor devices are composed of N-type and P-type semiconductors. Semiconductors are materials with both electrical conductivity and a lack of electrical conductivity. The lack of conductivity prevents the flow of current.

Modern-day semiconductors are used to manufacture computers, electronics, cell phones, and much more. They are made from two main materials, silicon and germanium, and minor compounds.

N-Type Semiconductor

N-type semiconductor refers to a semiconductor device containing at least one N-type electrical component. N-type semiconductor uses N-type doping to create a p-n junction, which is the starting point for most semiconductor electronics. N-Type Semiconductors are made of materials like silicon.

P-Type Semiconductor

P-type semiconductor refers to a semiconductor in which all elements are positively charged (e.g. phosphorus). P-type semiconductors are a type of semiconductor crystal material that is used to produce diodes. A p-n junction is a device that acts as a rectifier or a diode and is used in many electronic circuits. As the name suggests, in a P-type semiconductor, the dopants are positive ions of atoms such as phosphorus, arsenic, bismuth, selenium, or tellurium.

Major Categories of Semiconductors

Semiconductor devices can be grouped into three major categories: electronic components, computers, and communication devices. These are generally fabricated by the same processes.

The most important applications of modern semiconductors are in computer technology in the form of microprocessors and computer memory. In consumer electronics, it is used in digital television, digital audio, digital video, and wireless communication (McDowell and Reinders 2012), which are all based on an understanding of the basic principles of semiconductor devices.

Conductivity of a Semiconductor

Semiconductors are materials, metals, or compounds of these, with low electrical conductivity compared to other materials. When a semiconductor contacts other materials, it allows the flow of electrons with the lower energy band referred to as the conduction band.

Developments in the Field of Semiconductors

In the past few decades, the semiconductor industry has expanded to encompass a variety of applications. Such applications include the use of semiconductors in computers, which have become the most common and important application of this industry. However, other applications, such as incorporating semiconductors into automobiles, cellular phones, and other electrical devices, are also becoming more prevalent.

Semiconductor Doping

Doping is the process of adding impurities to a semiconductor to modify its electrical properties. Doping is usually done to control the conductivity of the semiconductor and to change the number of charge carriers.

Doping is done primarily to increase the electrical conductivity (and thus decrease its resistance) in silicon and compound semiconductors, including gallium arsenide and indium phosphide. Doping is done when a particular property of a material is desired. 

The purpose of doping is to create a heterogeneous region in the material. The region created by the doping is called the intrinsic region and has a very low electrical resistance.

The three most common dopants are boron, phosphorus, and arsenic, known as trivalent dopants. While the P-type and N-type elements can be doped by either of the two, the doping of the P-type requires a pentavalent impurity and the doping of the N-type requires a trivalent impurity. We can introduce impurities by adding them to the silicon crystals, by implanting them into the semiconductor, or by diffusion.

Effects of Doping

1. It increases the performance of semiconductor devices.

2. The effects of doping include an increase in hole mobility and a decrease in the threshold voltage, making the devices more responsive and improving their electrical properties.

3. Doping affects the electrical properties of the semiconductor by adding impurities in the form of atoms of different atoms.

4. Doping elements into silicon alters its conductive characteristics.

Conduction of a Doped Semiconductor

The conduction properties of a doped material can be understood by considering the semiconductor as a lattice of randomly located electrons. Impurities act as trapping sites for electrons. The free electrons are mobile in the bulk region and cannot move in the regions near the impurity atoms.

Conclusion

Doping is a common technique used to manufacture semiconductor devices such as transistors, diodes, and integrated circuits. The main goal of doping is to change the electrical properties of the semiconductor by adding impurities, which change the concentration of charge carriers or other electrons (n-type) or holes (p-type). This affects the conductivity of the material and hence its electrical properties.