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Short Communication | Open Access
  • Available online freely | Peer Reviewed
  • Quantum Dots- Tiny Semiconductor Nanodots

    Nida Tabassum Khan 1       Muhammad Jibran Khan 1    

    1Department of Biotechnology, Faculty of Life Sciences and Informatics, Balochistan University of Information Technology Engineering and Management Sciences, (BUITEMS), Quetta, Pakistan

    Abstract

    Quantum dots can be defined as semiconductor nanostructures which are artificial in nature and ranges from 2-10 nm in size. These tiny nanocrystals become excited under illumination and emits colors of different wavelength. Quantum dots possess unique properties determined by their structure (hollow or solid), size, shape and composition. Fabrication of Quantum dots is achieved by several methods such as electron beam lithography, epitaxy or by means of colloidal synthesis.

    Received 04 Sep 2019; Accepted 18 Sep 2019; Published 19 Sep 2019;

    Academic Editor:Muhammad Humayun, Huazhong University of Science and Technology, China.

    Checked for plagiarism: Yes

    Review by: Single-blind

    Copyright©  2019 Nida Tabassum Khan, et al.

    License
    Creative Commons License    This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

    Competing interests

    The authors have declared that no competing interests exist.

    Citation:

    Nida Tabassum Khan, Muhammad Jibran Khan (2019) Quantum Dots- Tiny Semiconductor Nanodots. Journal of Advances in Nanotechnology - 1(2):1-4.
    Download as RIS, BibTeX, Text (Include abstract )
    DOI10.14302/issn.2689-2855.jan-19-3012

    Introduction

    The word ‘Quantum’ itself is derived from a Latin word meaning ‘amount’ and can be defined as small unit of physical property like energy or matter 1. In 1900 physicist Max Planck discovered that like matter radiation existed in discrete units of energy, hence named these units as “quanta” 2. Similarly, quantum dots can be defined as semiconductor nanostructures which are artificial in nature and ranges from 2-10 nm in size 3, 4.These tiny nanocrystals become excited under illumination and emits colors of different wavelength 5. Quantum dots possess unique properties determined by their structure (hollow or solid), size, shape and composition 6.Sometimes these are also referred as artificial atoms 7. Quantum dots have different crystalline lattice structures so when pressure is applied they form very thin semiconductor films 8. As a result, the flat film later due to stress tends to separate into dots in three dimensions 9.

    Physiochemical Properties of Quantum dots is mentioned in Table 1.

    Table 1. Physiochemical Properties of Quantum dots
    S.no Physiochemical Properties  
    1 Size Microscopic, 2-10nm (10-50 atoms) 10
    2 Configuration Confined in three-dimensions 11
    3 Highly tunable Variable core sizes make them give off different colors by tuning/changing the characteristic wavelength of emitted light 12.
    4 Excitable Can excite to higher energy level to emit light of respective wavelength 13
    5 Shapes Various including cubes, spheres and pyramids 14
    6 Resistance Resistance to photo-bleaching, photo-degradation and chemical- degradation 15, 16.

    Types of Quantum Dots

    There are 3 types of Quantum dots on the basis of their composition and structure 17.

    Core-Typed Quantum Dots

    Quantum dots that have internally uniform structures which is composed of a single material 18. They have variable electro/photo luminescence e.g. Metal chalcogenides 19.

    Core-shell Quantum Dots

    Also known as Core-Shell semi-conducting nanoparticles having variable photophysical properties e.g ZnS20

    Alloyed Quantum Dots

    Multicomponent semiconductor nanoparticles e.g. CdS-Se/ZnS 21

    Fabrication of Quantum Dots

    There are 3 main approaches through which quantum dots can be prepared

    1. Electron beam lithography 22

    2. Colloidal synthesis 23

    3. Epitaxy such as Vapor Phase epitaxy, liquid phase epitaxy,molecular beam epitaxy etc 24, 25

    Applications of Quantum Dots

    Used in Solar cells and photo-voltaic e.g. Graphene quantum dots 26.

    Used as fluorophores which helps in bio-sensing and bio-tagging 27.

    Used as a catalyst to form hydrocarbons 28

    Luminescent quantum dots (LQD) are used in high quality displays and lighting systems 29

    Quantum computing uses quantum computer that store information in quantum bits 30.

    Magnetic quantum particles are used in memory chips 31

    Used in communication devices like lasers 32.

    Have biological applications including in vivo and invitro imaging, DNA assays and microarrays,labelling tumors , diagnosis /treatment of cancer , drug delivery 33, 34, 35, 36

    Quantum dots have many exceeding rewards, but they do have drawbacks like they are costly, toxic, may cause environmental pollution etc 37.

    Conclusion

    Due to their excellent intrinsic and extrinsic properties, Quantum dots continues to amaze researchers with their immense applications.

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