Super Lattices and its applications

Project Title

Super Lattices and its applications

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

Superlattices are made by sandwitched semi-conductor materials. As they interact with the nanoparticles it is possile to create new materials and sensors with beneficial physical properties. However, it has been difficult to make the structures thermodynamically stable. A team from the University of Michigan, IBM and Columbia University recently created ten novel binary nanoparticle superlattice materials. 

The electronic and optical properties of crystals are determined by the chemistry of the different atomic constituents, the crystal structure (i.e., the relative positions of the different atoms), and the distance over which a basic unit of the crystal structure is repeated. In semiconductors such as silicon and gallium arsenide these repeat distances are of the order of two atomic spacings, and the naturally occurring forms of these materials at room temperature are in the diamond and wurtzite crystal structures, respectively. It is now possible to grow semiconductor crystals atomic layer by atomic layer, controlling the chemical composition within each layer, and, for example, to interleave two semiconductor compositions with prescribed repeat distances (say repeats of two atomic layers of one and four of the other). The electronic and optical properties of such engineered crystals, called superlattices, now depend in part on the repeat distances, and the semiconductor device performance can be tailored. This is leading to second quantum industrial revolution where the devices are developed on tailored materials keeping in view the requirement of our applications. For example, while gallium arsenide lasers operate in the infrared, and aluminium arsenide does not lase at all, repeated multilayers of the two lase in the red. Even a single interface between semiconductors—a heterojunction—can be used to trap electrons and force them to move in two, rather than three, dimensions. The physics of such constrained motion is quite different from that of the motion in bulk semiconductors, and lower-noise, more temperature-stable devices have emerged. 

Project Objectives  

1. Binary nanoparticle superlattices are periodic nanostructures with lattice constants that are shorter than the wavelength of light and can be used for preparing multifunctional meta-materials. These superlattices are fabricated from synthetic nanoparticles and, even though some biohybrid structures have been developed, including biological binary blocks into binary nanoparticle superlattices, remains a challenge. These Protein-based nanocages offer a complicated yet monodisperse and geometrically well-defined hollow cage that we want to use for the encapsulation of different materials. 

2. In  binary superlattices, we are focused to combine metals, semiconductors, ferroelectric, magnetic, dielectric and other materials. For instance, binary superlattices of semiconducting and magnetic nanoparticles are suitable for spintronic and magneto-optic data storage devices as well as quantum computer components, while superlattices comprising two different semiconductors can be used for a new generation of thermoelectric devices and solar cells. Binary superlattices can also be used for designing new effective catalysts with an accurate arrangement of catalytic centers 

Project Implementation Method

We are developing mathematical tools and numerical codes related to the project. In the beginning I have performed literature review and overview of necessary foundation techniques. 

We have applied Schrodinger equation to study the dynamics of electrons in semi-conductor materials. Using the wave equation  we have develped basic knowledge related to one dimenional box, and step potential barrier. These topics have their importance in modelling simple systems such as quantum wires and quantum dots. 

Later, the technique was extended to  two and then many potential barriers, potential wells, bands and band spectrum. After gathering specific knowledge about simple systems using schrodinger equation we jump to complex systems and apply perturbation theory. Before we open complicated mathematical calculations we have studied various properties of wave function we are dealing with, such as reflection and transmission currents and the transmitivity and reflectivity due to the devices. These techniques are helpful to explain the properties of super-lattices. Based on these concepts we are ready to study various complex and hybrid semi-conductor systems such as super-lattices and their interaction with nano-particles. 

Benefits of the Project

Research on superlattices carried out by our group will lead to general advances in the growth and fabrication of fine-period heterostructure devices. This is a very fruitful area of research which will benefit from the exchange of views and information dissemination within the members of research group. The understanding of the underlying physical processes of vertical transport in superlattices will also broaden the base knowledge in low dimensional semiconductor structures. The hybrid super-lattices are seen as a necessary stepping-stone towards the exploitation of superlattice structures for the enhancement of existing devices and for realising novel device concepts. The devices of interest to the group are perceived to have potential for the field of nano- and micro- electronics, opto- electronics for future requirements in information technology.

Technical Details of Final Deliverable

It is possible to produce superlattices with several distinct geometries using different approaches, and the number of achievable lattices can also be increased by formulating a suitable strategy. 

Nanoparticles in a binary lattice can be substituted with spacer entries that imitate the behavior of the nanoparticles being replaced, even if they do not have an inorganic core. Including spacer entities within a known binary superlattice will effectively delete one set of nanoparticles without impacting the positions of the other set. 

Final Deliverable of the Project Hardware SystemCore Industry ManufacturingOther Industries IT Core Technology NeuroTechOther TechnologiesSustainable Development Goals Industry, Innovation and InfrastructureRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	80000
Mathematica software	Equipment	1	70000	70000
stationary, thesis write up and publication	Miscellaneous	1	10000	10000