Research

Materials

For the Student: Materials form the basis of all technologies. The research happening at CeNSE provides varied opportunities in the fields of electronics, photonics and the emerging quantum world for metallurgists, material scientists and engineers to evolve and build upon the platform they have acquired in their undergraduate education. Students from other disciplines who have not had exposure to the materials aspects, get a chance to do so.

To illustrate the point, GaN has emerged as the second most important semiconductor since silicon. It is used in light emitting diodes or LEDs, power electronics for electric vehicles and RF electronics for 5G. Materials scientists in CeNSE try to understand the way GaN thin films nucleate and grow, to in turn control the dislocation density in the layers. Electronics engineers for their part try to understand how leakage current flows through these defects. Very often the line is completely erased and by the time a student graduates he/she is neither the material not the electronics engineer but both.

Such collaboration is happening in CeNSE not only in GaN based technologies but in oxide materials for photonics, oxide and nitride based piezo-MEMS (micro- electro- mechanical systems), 2D materials for the emerging quantum world and NEMS, materials for sensors, packaging, and photovoltaic applications. The image below shows these networks. Click on any of the links to understand the collaborative nature of the work. Prof. Srinivasan Raghavan grows GaN thin films and tries to understand how stresses and defects evolved during nucleation and growth. Prof. Digbijoy Nath makes transistors using these GaN film and measures I-V electronic characteristics. Together they establish correlations between device performance and material microstructure.

For Industry: CeNSE has a wide variety of expertise in materials such as GaN for RF and power electronics, oxides for piezo MEMS, NEMS, system on chip, sensors, photonics, photovoltaic materials including Si and perovskites, quantum materials and organic molecules for neuromorphic computation. Faculty members work on development of systems – CVD, PLD, MBE, PVD reactors – for synthesis of materials, developing process flows for fabricating devices, packaging them and integrating them in systems. The image below shows the linkages between the faculty members and their collaboration for a particular area of research.

GaN for RF and Power electronics
A group of 10 faculty members work on all aspect of GaN technology from wafer development on Si and SiC to device fabrication for power and RF applications to system integration for DC-DC convertors and RF MMICs. (Digbijoy Nath, Navakanta Bhat and Srinivasan Raghavan)

AlN for piezo MEMS
Researches are working on development of AlN on Si epitaxial layers with state-of-the-art D33 characteristics for next generation piezo micro-electro mechanical devices.

Oxides for MEMS
We develop various piezoelectric and other electromechanical oxide thin films such as PZT (lead zirconium titanate), BaTiO3 and alloys that give large electromechanical transduction coefficients. We are also working on designing newer materials such as doped-CeO2 where functions such as giant electromechanical functions are engineered by defects. These materials are less toxic, eco-friendly and Si compatible, making them very favoured candidates for partially replacing the more standard materials such as PZT. The eco system in CeNSE allows us to fabricate real MEMS devices, and test these materials for applications Oxides for Photonics: Researchers at CeNSE are collaborating on developing epitaxial functional oxide thin films, such as Barium Titanate, on silicon substrates for integrated photonics applications. Such integrated photonic applications allow the manipulation of light on chips using electric fields for electro-optic modulators.

Perovskites for Optoelectronics
Lead-halide perovskites are a new class of defect-tolerant materials that are revolutionizing optoelectronics. Perovskite solar cells and light-emitting diodes are extremely efficient, even when the material is structurally defective. The films can be cast at near room temperature on virtually any substrate – glass, steel, or plastic, enabling new class of wafer-less devices. CeNSE faculty are investigating new 3D and 2D versions of the perovskite to enhance stability. We are also searching for lead-free versions with lower toxicity. We are also synthesizing large-bandgap perovskite for light-emitting diodes.

Quantum Materials
Using ideas of electron correlation, topology and disorder, Prof. Pavan Nukala’s group works on developing various oxide-based quantum materials. Materials showing Mott metal insulator transitions (VO2), that can be engineered as neuronal oscillators, ferroelectric heterostructures that host skyrmions (topology) for memory applications, electrocaloric materials for low temperature cryogenic cooling applications and disordered materials with Andersons localization physics for phase change memory applications are some of the active projects.

Materials for Neuromorphic Applications
We develop materials (such as vanadium oxide, nickelates) for synaptic devices and neuronal oscillators, using ideas of quantum correlations and disorder. We also use heterogenous features in various materials to realize unstructured neural networks. Prof.’s Pavan Nukala, Sushobhan Avasthi, Srinivasan Raghavan and Saurabh Chandorkar work on these endeavours.