Rampi Ramprasad - Research
Dr. Ramprasad�s main research and teaching interests lie in the areas of Computational Materials Science and Materials Theory. His research areas are inter-disciplinary, spanning Materials Science, Physics, Chemistry and Electrical Engineering. Areas of particular interest include:

1. Surfaces/Interfaces: The International Technology Roadmap for Semiconductors (ITRS) has placed stringent demands on the next generation of logic, memory and RF capacitor devices, all of which require few to several nanometer thick dielectric films with high capacitance density. In response to these demands, the semiconductor industry is considering replacing conventional dielectric materials by other high permittivity (or high-k) dielectrics such as Ta2O5 and HfO2. However, electronic conduction through nanometer scale thin dielectric films and across metal-dielectric interfaces under an applied electric field both degrades the device performance and causes breakdown of the dielectrics in the long run. Furthermore, mechanisms underlying conduction & breakdown phenomena are numerous and have their origins at the electronic and atomistic level. Examples of such electronic / atomic level events include defect creation and dynamics, defect-defect interactions, and band offsets, Fermi level pinning & polarization at metal-dielectric interfaces. Present studies focus on performing detailed atomic level simulations, and using these results in meso-scale models of electronic transport and dielectric breakdown.

2. Nano-materials: A new perspective on nano-materials is to focus on the collective properties of an array of nano-particles rather than on the novel properties of each individual nano-element, while still carefully accounting for the physics underlying the �nano� nature of each of the constituents. Such a collective treatment requires using both mesoscale theories, such as the effective medium theory, and quantum electronic structure methods. Current investigations center around effective media composed of an array of nano-particles or nanotubes in a dielectric matrix, and effective properties such as dielectric constant, permeability, etc, as a function of nano-material type (chirality in the case of nanotubes, for instance) and composition . Such effective media have applications in present day and future semiconductor and wireless telecommunications technologies.

3. Electromagnetic crystals, acoustic crystals and meta-materials: The next generation of semiconductor, wireless and opto-electronic devices will require complex signal manipulation, propagation and processing. Electromagnetic or acoustic waves can be manipulated in novel ways by systems that have periodic or quasi-periodic variations in their material properties such as permittivity, permeability or conductivity (in the case of electromagnetic crystals) and mechanical properties such as density and bulk modulus (in the case of acoustic crystals). Our studies will involve mapping the relationship between the physical and structural properties of these crystals on the one hand, and their electromagnetic and acoustic response on the other.

In addition, Dr. Ramprasad will also be actively involved in (i) the development of advanced theoretical methods that bridge length & time scales by linking quantum mechanics based methods (such as density functional techniques) with phenomenological methods, (ii) developing efficient techniques to study electromagnetic and acoustic wave propagation in crystals and (iii) parallel computing.