Quantum Dots- Tiny Semiconductor Nanodots - Quantum Dots- Tiny Semiconductor Nanodots - Open Access Pub

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. DOI10.14302/issn.2689-2855.jan-19-3012 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