Objectives

The objective of our research is to study a novel 3D Dirac semimetal as an active layer of electronic devices for RF applications. Cd3As2 is a Dirac semimetal with high mobility and an exceptionally high Fermi velocity. Our goal is to utilize these unique electronic properties for RF transistors.    

Approach

We are working to achieve the goal in two ways. Firstly, we can use Cd3As2 as the channel layer of planar FET structures. In this way, we can use the high mobility and Fermi velocity to achieve the high current density and high transconductance that are necessary for RF applications. Secondly, we can use Cd3As2 as the base layer of a hot electron transistor (HET). A HET is a BJT-like transistor with unipolar transport. Low sheet resistance and high fermi velocity could be helpful for extreme base scaling to achieve very small base transit time. This could be helpful access terahertz regime.

Collaboration with Prof. Mark Rodwell and Prof. Umesh Mishra helps us to design and modify our experiments.

Accomplishments

We have already demonstrated the first Cd3As2 channel FET. The device shows current density greater than 1A/mm. As Cd3As2 is a gapless material, it is not possible to turn off the device completely. We have demonstrated current modulation of more than 50% at room temperature. The first generation transistors were limited by interface traps. We have developed a fabrication process that lowers the interface traps and improves device performance.    

Team Leader

Susanne Stemmer

Susanne Stemmer is Professor of Materials at the University of California, Santa Barbara. She did her doctoral work at the Max-Planck Institute for Metals Research in Stuttgart (Germany) and received her degree from the University of Stuttgart in 1995.  Her research interests are in the development of scanning transmission electron microscopy techniques, molecular beam epitaxy, functional and strongly correlated oxide heterostructures, and topological materials.  She has authored or co-authored more than 250 publications.  Honors include election to Fellow of the American Ceramic Society, Fellow of the American Physical Society, Fellow of the Materials Research Society, Fellow of the Microscopy Society of America, and a Vannevar Bush Faculty Fellowship of the Department of Defense.

Publications

Publications

Material pending.

All Publications