What is Semiconductor Material : Types & Their Applications

Semiconductors are formed using different materials with different properties. So, the materials used in semiconductors are intrinsic & extrinsic. The intrinsic semiconductor material is very pure chemically, possesses less conductivity & includes less number of charge carriers whereas extrinsic material has less purity and uses doping to make an extra or a shortage of electrons. An intrinsic semiconductor is known as P-type whereas an extrinsic semiconductor is known as an N-type semiconductor. So, the electrons in N-type semiconductors are excess whereas P-type have a shortage. This article discusses an overview of semiconductor material, a list of materials, and its applications.

What Are Semiconductor Materials?

The materials which have conductivity between conductors and insulators are known as semiconductor materials. These are pure elements like silicon (Si) or germanium (Ga), or compounds like gallium arsenide (GaAs) or cadmium selenide (CdSe). In the doping process of pure semiconductors, small amounts of impurities can be added to make huge changes within the material’s conductivity.

The materials conductivity mainly lies in between the conductivity of insulators & conductors. Semiconductors materials have some useful properties which are used in the designing of solid-state devices like transistors, diodes, etc.

Semiconductor Materials in Periodic Table

In the periodic table of chemical elements, semiconductor materials are available in different groups. So the properties of these materials are associated with their atomic characteristics & also vary from one group to another group. Designers & researchers utilize the benefits of these dissimilarities to enhance the design & select the best material for a required application.

The semiconductor materials are atoms within a semiconductor that are available from different groups in a periodic table as a combination of group III & V or either group IV or combinations of group II & VI. In the periodic table, different semiconductors are designed with different materials from several groups, but their properties vary between different semiconductors.

In the periodic table, Silicon (Si) material is a group IV element and it is the most frequently used semiconductor material because it forms the base for ICs or integrated circuits. So, most of the solar cells are Si (Silicon) based. The diagram of semiconductor materials in the periodic table is shown below.
In a periodic table section, common semiconductor materials are indicated in the above figure.

Generally, a semiconductor is a single element like silicon, germanium, a compound like GaAs, CdTe/ InP, or an alloy like AlxGa(1-x)As/ SixGe(1-x), where ‘x in these materials are the part of the specific element that ranges from zero to one.

List of Semiconductor Materials

The list of semiconductor materials is discussed below.

Germanium (Ge)

The semiconductor material like germanium is from group IV in the periodic table. This material was used in early devices which range from diodes to early transistors. Diodes show a temperature coefficient & higher reverse conductivity so that early transistors could experience thermal runaway. It provides superior charge carrier mobility as compared to silicon, so used in some RF-based devices.

Silicon (S)

Silicon material is a group IV element in the periodic table of chemical elements and it is the most frequently used semiconductor material. These materials are very simple to fabricate and offer the best mechanical & electrical properties. When these materials are used in ICs, then it forms good quality silicon dioxide for insulation layers In between various active elements of the chip.

Gallium Arsenide (GaAs)

After Si, the Gallium arsenide semiconductor is the most widely used material and it is III-V group element in the periodic table. It is broadly used in high-performance-based RF devices where the high electron mobility of this element is used. In other III-V semiconductors, it is also used as substrate-like GaInNAs & InGaAs. This material has less hole mobility as compared to Silicon. It is also quite complex to fabricate & also increases the GaAs devices cost.

Silicon Carbide (SiC)

Silicon carbide material is an IV group element in the periodic table. These elements are used in power devices wherever their losses are considerably less & high operating temperatures as compared to Si-based devices. This material has a breakdown capacity as compared to silicon which is above ten times. The silicon carbide material forms are used in blue and yellow color LEDs.

Gallium Nitride (GaN)

Gallium Nitride or GaN material is an III-V group element in the periodic table. It is most widely used in microwave transistors wherever maximum powers & temperatures are required and also used in microwave ICs. This semiconductor material is hard to dope to provide p-type regions & also responsive to electrostatic discharge however quite not sensitive to ionizing radiation. This material has been used in blue color LEDs.

Gallium Phosphide (GaP)

Gallium Phosphide or GaP semiconductor material is an III-V group element in the periodic table. This material is used in early low brightness to medium based LEDs which generate different colors based on the addition of dopants. Pure GaP generates green light, nitrogen-doped emits yellow-green and ZnO doped emits red color.

Cadmium Sulphide (CdS)

Cadmium Sulphide or CdS semiconductor material is an II-VI group element in the periodic table. This material is used in solar cells & photoresistors.

Lead Sulphide (PbS)

Lead Sulphide or PbS semiconductor material is an IV-VI group element in the periodic table, used in early radio detectors called as Cat’s Whiskers’ wherever a tip contact was designed by using thin wire on the galena to give signals rectification.

Types of Semiconductor Material

There are two types of semiconductor material like the following.

Intrinsic Semiconductor Material

An intrinsic semiconductor material is made chemically very pure and it is one of the main features in it. Thus, it possesses less conductivity level with a very less number of charge carriers like electrons and holes in equal quantities.

In this semiconductor material, the number of charge carriers can be determined through the material properties themselves as an alternative to the impurities. So, the number of energized electrons is equivalent to the number of holes (n = p) which are also called undoped or i-type semiconductors.

The most commonly used intrinsic semiconductor materials are Si & Ge and they include 4 electrons in their valence shell which are known as tetravalent. These two materials are the IVth Group elements in the periodic table & the atomic numbers of these materials are 14 & 32 respectively.

Extrinsic Semiconductor Material

Extrinsic semiconductor materials can be formed by adding a small amount of impurity to the basic intrinsic material. In this material, the bandgap can be controlled by adding small impurities to the material which is known as doping.

This ‘doping utilizes an element from a periodic table so that it will have either less or more electrons within the valence band as compared to the semiconductor itself. So this will create either shortage or an excess of electrons.

Extrinsic semiconductor materials are classified into two types based on the type of added impurity like P-Type extrinsic semiconductor & N-type extrinsic semiconductor.

Please refer to this link to know more about Intrinsic & Extrinsic Semiconductor

P-Type Extrinsic Semiconductor

A P-type extrinsic semiconductor can be formed by adding a small amount of trivalent impurity to a pure semiconductor. The impurity which is added mainly includes three valence electrons. So, for instance; if an atom-like Boron (B) is added to the germanium (Ge) atom, then three valence electrons will get connected with the germanium atoms to form 3 covalent bonds. However, another electron within the Ge atom will stay without forming a bond. In an atom, when there is no electron to form a covalent bond, then that space is called a hole.

Please refer to this link to know more about P-type Semiconductor

N-Type Extrinsic Semiconductor

The N-type semiconductor can be formed by adding a small amount of pentavalent impurity to a pure semiconductor. So, this impurity includes five valence electrons.

For instance, if an atom-like Arsenic is added to the ‘Ge’ atom, then four valence electrons will be connected through the germanium atoms whereas one single remaining electron will stay free.

Please refer to this link to know more about N-type Semiconductor

Latest Innovations of semiconductor Materials

At present, the silicon semiconductor material is reaching the boundary of its value. So, the investigation into new semiconductor materials is ongoing. Some of the latest innovations of materials are listed below.

• High-power gallium nitride material is used for quick power conversions, more efficient electric grid systems because of its maximum critical energy field.
• The semiconductor materials like Antimonide & bismuthide are used in enhanced IR sensors military & medical fields.
• Graphene material can beat silicon like a universal semiconductor material.
• Pyrite element is used to change the earth element like cadmium telluride to use in solar cells however they have limited supply. So, the Pyrite element is inexpensive, nontoxic & abundant.

Semiconductor Material Parameters

While designing integrated circuits and electronic devices, information about semiconductor materials must be available. Before the fabrication process starts, the semiconductor material has to be distinguished in terms of different parameters like electrical, optical & thermal.

The essential parameters are the type of conductivity, mobility, resistivity, concentration & lifetime of the carrier. Some other additional parameters are the energy gap of semiconductors, light absorption coefficient, impact ionization coefficient & refraction index.

Advantages & Disadvantages

There are different semiconductor materials are available in the market like silicon, germanium, gallium arsenide, silicon carbide, gallium nitride, etc. Each material has some advantages and disadvantages. So here, some of the material’s advantages and disadvantages are discussed below.

The advantages of silicon material are;

• Silicon material cost is low
• Silicon has high efficiency
  In silicon, large wafers can be handled very securely without any harm because of their hardness
• Silicon is stable thermally upto 1100 degrees centigrade.

The disadvantages of a silicon material are;

• It requires crystalline
• Easily broken
• Substrates are limited
• It is costly to produce Si crystals.
• Short life cycle
• Toxic substances are generated

The advantages of a germanium material are;

• Pure germanium is gray-white, hard, and brittle metalloid.
• Its crystalline structure is like a diamond
• Germanium is constant in water & air
• It is not affected by acids & alkalis apart from nitric acid.
• By using Germanium material, first, the transistor action was observed. So it is one of the most essential semiconductor materials.
• High atomic number, so it enhances the gamma-ray interaction probability.
• Large crystals
• The material used in this is grey metallic

The disadvantages of a germanium material are;

• Its energy resolution is responsive to radiation damage
• Less efficiency for higher energy-based gamma rays.

Applications

The applications of semiconductor materials include the following.

• Semiconductor materials are used to manufacture different electronic components in electronic devices.
• These materials are mainly used for switching, energy conversion, and amplification, sensors, etc.
• The common components and products are made with semiconductor materials like diodes, field-effect transistors, integrated circuits, junction field-effect transistors, bipolar transistors, LEDs (light-emitting diode), MOSFETs (metal-oxide-semiconductor FETs), SCR (silicon-controlled rectifiers), etc.
• Semiconductor materials are used for different components in electronic devices which are used almost in major industries. Different industrial sectors depend on semiconductor materials like energy, artificial intelligence, communication, clean energy, military, health care, computing & the Internet of Things.

Thus, this is all about an overview of semiconductor materials, types, and their applications. We know that there are different semiconductor materials are available but Silicon or Si is most frequently used over Germanium in different electronics manufacturing applications because, the energy band gap of Si is 0.7ev, generation of thermal pair is smaller, available easily in nature, less noise, SiO2 formation is simple. So, Silicon material is used to manufacture many electronic components to use in different circuits like resistors, diodes, capacitors, transistors, switches, etc. Here is a question for you, what are the characteristics of semiconductor materials?