Quantum dots

What exactly are quantum dots and how can they be used? This article will explain it to you.

 

Definition

Quantum dots are structures on nano-scale mostly made out of semiconducting materials but the features of them can be adjusted very precisely.
Quantum dots are no real material but rather a type of material that exhibits quantum effects. As a result of these quantum effects the nanocrystals show very interesting optic, magnetic and electronic features. The following passage will tell you more about this.

Features

Quantum dots have a size of 1-1000 nm and there are three main groups of quantum dots.

III-V-Semiconductors

Quantum dots of this type are made out of elements of the third (boron, aluminium, gallium and indium) and fifth main group (nitrogen, phosphorus, arsenic, antimony and bismuth). 
The most interesting quantum dot of this type is gallium arsenide (GaAs) because of its ability as strengthen medium in lasers. In addition to that it can be used as light source in the optic data handling but it will still only be used for special application and not as a replacement for silicon in the semiconductor industry.
One can produce these quantum dots by using the Molecular beam epitaxy, which is an epitaxy method which means that both elements get evaporated.

II-VI-Semiconductors

These quantum dots are made out of elements of the second subgroup (zinc, cadmium) and the sixth main group (oxygen, sulfur, selenium and tellurium). The most famous representatives of this group are cadmium selenide (CdSe) and cadmium telluride (CdTe) but also zinc oxide (ZnO), which is already used in nanoparticles today, maybe used for quantum dots in the future.

These quantum dots could be used in electronics, photonics, photovoltaics and biomedical. Especially the fluorescence abilities of them make them interesting for any type of display or screen.

They can be produced on the same way like quantum dots made out of III-V-semiconductors.

Si-quantum dots

Si quantum dots aren't so far developed yet but they have a great potential to get integrated into silicon electronics for example in processors or optic sensors. They can also be used in photovoltaics to get higher efficiencies but the problem is the high price which is why these solar cells are only used in the space technology today. 

These quantum dots can be produced by bringing more silicon ions into a silicon oxide matrix and then everything gets heated until the crystals form themselves.

Conclusion

Quantum dots seem to have a great future but we mustn't forget that most of them include toxic elements like cadmium. So as a result one can say that quantum dots will be part of our future but probably only in applications where we don't come in direct contact with them.