Semiconductor Material – Working & Its Applications

What is semiconductor material?

Semiconductors are materials that have a conductivity between conductors (generally metals) and nonconductors or insulators (such as most ceramics). Semiconductors can be pure elements, such as silicon or germanium, or compounds such as gallium arsenide or cadmium selenide. In a process called doping, small amounts of impurities are added to pure semiconductors causing large changes in the conductivity of the material.

Due to their role in the fabrication of electronic devices, semiconductors are an important part of our lives. Imagine life without electronic devices. There would be no radios, no TVs, no computers, no video games, and poor medical diagnostic equipment. Although many electronic devices could be made using vacuum tube technology, the developments in semiconductor technology during the past 50 years have made electronic devices smaller, faster, and more reliable.
Semiconductor Materials are basically of two types

Single-Crystal Semiconductors (Pure Semiconductors)

Compound Semiconductors (Compound of two or more semiconductors)

- 1. Gallium Arsenide (GaAs)
  2. Cadmium Sulfide (CdS)
  3. Gallium Nitride (GaN)
  4. Gallium Arsenide Phosphide (GaAsP)

The three semiconductors used most frequently in the construction of electronic devices

Germanium (Ge)

Was used almost exclusively in the first few decades after the discovery of the diode in 1939, and the transistor in 1947, because Germanium was
But, diodes and transistors constructed using Germanium as the base material
Suffered from low levels of reliability due to its sensitivity to changes in temperature.

Silicon (Si)

Had improved temperature sensitivities.
But, the refining process for manufacturing silicon with very high levels of purity was still in the development stages.
In 1954 the first silicon transistor was introduced.
Silicon is not only less temperature sensitive but also one of the most abundant materials on earth, which removes any concerns about availability.

Gallium Arsenide (GaAs)

As the field of electronics became increasingly sensitive to issues of speed, computers were operating at higher and higher speeds, and communication systems were operating at higher levels of performance
Gallium Arsenide(GaAs) was found as A semiconductor material capable of meeting these new needs.
The first gallium arsenide transistor was developed in the early 1970s.
This new transistor had speeds of operation up to five times that of Silicon.
Silicon has the benefit of years of development and is the leading semiconductor material for electronic components and ICs.
Silicon is still the fundamental building block for Intel’s new line of processors.

Semiconductor atoms are bonded in a periodic structure.
The electrons surrounding each atom are part of a covalent bond.
The electrons surrounding each atom are part of a covalent bond.
On average, there are 4 valence electrons per atom.
On average, there are 4 valence electrons per atom.
Extremely tiny traces of impurity can have a drastic effect on a semiconductor’s electrical properties.
Modern semiconductors are the purest solid materials.
In silicon, the unintentional impurity is less than 1 atom per 109 silicon atoms.
Purposely added dopant atoms range from 1 atom per 108 – 103 semiconductor atoms.