The BRADLEY DEPARTMENT of ELECTRICAL and COMPUTER ENGINEERING

Research Areas

By studying less-common materials and combinations of materials and creating the small devices that use them, our researchers in microsystems, optoelectronics, and devices are making computers and solar cells more efficient, improving the packaging and manufacturing of power electronics, rapidly analyzing gases, developing better solid-state lights, and furthering our knowledge of cancer. Research in this area includes microelectromechanical systems (MEMS), microfluidics, electronic packaging, and semiconductor design, fabrication, and testing.

Current Research

MEMS

Research in the VT MEMS Lab focuses on using MEMS, nanotechnology, and lab-on-a-chip devices for applications including real-time gas analysis, single-cell biophysical characterization, pathogen enrichment, and cancer engineering.

Using atomic force microscopy, we have shown that metastatic breast cancer cells become more softened when subjected to cyclic nanoindentations while normal breast cell lines display mechanical stiffening. This method could identify metastatic cells with more than 90 percent confidence.

We have also recently developed a chip containing a MEMS-based semi-packed column with atomic layer deposited stationary phases and a plasma-based photo ionization detector. The chip is only 3 cm x 1.5 cm, and has shown multi-component separation with a minimum detection limit of 10 pg under temperature and pressure programmed runs.

Better Solar Cells

In the search for more efficient solar cells, we have identified a path towards performance improvements with new Schottky materials such as ruthenium oxide, nickel oxide, and ruthenium-nickel oxide. We have demonstrated InGaN/GaN Schottky barrier solar cells without the need for p-type doping using Au/Ni transparent conducting films as "Schottky metal."

Improved memory

The greatest bottleneck in a chip's communication is the path from logic to memory, which causes latency issues. We are shortening this path by determining the optimal material choices for a realization of memory within the back-end interconnect system.

In another effort, we are investigating the switching mechanisms in resistive ReRAM devices by analyzing the interdependence of critical threshold voltages. The goal is to tighten their distribution to make them employable for commercial memory applications and to replace the current nonvolatile memory based on floating gate technology.

We are also studying theoretical aspects of memristors, including the interactions between memristors in memresitive circuits for neuromorphic applications, or circuits that act like a brain's neurons.

Improved Transistors

Because we are reaching the limits of silicon transistor technology, ECE researchers are exploring new materials and architectures to create smaller devices with greater speed and efficiency.

One method we are exploring is growing materials such as Ge and InGaAs onto silicon to take advantage of both the years of research into silicon as well as the properties of the alternate materials. These transistors have the potential to provide much higher switching speeds and to operate at much lower voltage than devices made of silicon alone. Our current research on the novel Ge and InGaAs based transistor architectures heterogeneously integrated on Si using large bandgap III-V buffer architecture offer an unique advantage compared to any other technologies.

We are also developing tunnel Field-Effect Transistors(FET) using new materials and device architectures to provide further scaling of CMOS circuits. One of the most promising approaches is to reduce the power supply voltage by using a tunnel FET which operates at 0.3 V or less. This project is the first of its kind in low power research for implantable devices.