Structural, Electronic and optical properties of Semiconductor Nanocrystals

27 April 2007

The synthesis of nanocrystal is continuously increasing since last decade and while synthesizing the nanocrystal, the scaling of a property of the material that is different from microcrystalline as well as molecular size is also taken care off. In some semiconductor nanocrystal having particles in the range of 1 to 20 nanometer size range or less than the Bohr radius for the corresponding material, the scaling of certain property is observed

In a semiconductor nanocrystal, the particle size is reduced and therefore there is an increase in number of surface atoms to the total atoms or in other words the total surface area increases. Due to this increase in surface area a number of chemical bonds gets disrupted and some excess energy is created. This increase in energy is unfavorable and causes the nanocrystals to rearrange and form a metastable phase.

Actually, the nanochemistry has a lot of scope with surface phenomenon and in derivatized semiconductor nanocrystal,the internal crystalline structure is basically same as the macrocrystalline lattice but the nanocrystal will have entirely different electronic properties. It have been established that in nanocrystals the stable crystalline structure is largely responsible for their surface energy.

So, far various methods have been developed to synthesize semiconductor nanocrystals and lots of experiments have been conducted to study structural, optical and electronic properties. The main categories i.e. controlled precipitation in confined spaces, molecular precursors route and cluster building approach have been finalized. The future directions include the fabrication of functional nanodevices and their successful utilization in semiconductor applications.

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