Asif Islam Khan

Email: asif@eecs.berkeley.edu


I am a PhD student in the Department of Electrical Engineering and Computer Sciences at the University of California at Berkeley. I am advised by Professor Sayeef Salahuddin. I am also a member of the research group of Professor Ramamoorthy Ramesh and of Professor Chenming Calvin Hu. My CV is available here.

My research interests are to enable novel, functional, post-CMOS nanoelectronic devices by leveraging new physics and phenomenon in emerging multifunctional materials such as complex oxides, ferroelectrics/multiferroics and strongly correlated materials. Key ingredients of my research are high quality materials growth (primarily employing the pulsed laser deposition technique), innovative integration, fabrication and nano-characterization techniques. I envision a role at the center-stage that combines the best of complex oxides physics, electrical engineering and semiconductor technology.

Complex oxides show an unparalleled diversity of physical properties ranging from multistability to metal-insulator transitions to complex topological features. These materials by themselves and in conjunction with conventional and emerging semiconductors could enable unprecedented performance gains in electronics unachievable by traditional platforms and could lead to new computing paradigms. Towards that end, my graduate research focuses on novel nanoelectronic functionalities in archetypal ferroelectrics. Our work led to the first experimental demonstration and the first direct measurement of nonequilibrium negative capacitance in ferroelectric complex oxides (published in Nature Materials in 2014 and Applied Physics Letters in 2011). A negative capacitance oxide used as the gate insulator in a MOSFET could lead to a sub-60 mV/dec of sub-threshold swing-and hence an ultra-low power operation. Our work since 2008 along with other researchers worldwide establishes this new physical concept on a solid ground. The work is facilitated by epitaxial growth (pulsed laser deposition) of complex oxides (e.g. (Pb(ZrxTi1−x)O3, (Ba0.8Sr0.2)TiO3, SrTiO3, LaAlO3, BiFeO3 etc.) and their heterostructures and superlattices. This sets the stage for a possible new field, where different phase transition phenomena could be utilized to overcome the classical limitations of traditional electronics leading to highly energy efficient nano-devices/-FETs.

Our work also includes nano-architectonics based on ferro-electric/elastic domain walls. We studied the rich physics of domain dynamics in epitaxially strain tuned multiferroic thin films using specialized scanning probe microscopy (piezo-response force). We reported a new mechanism of electric field induced ferroelastic domain wallmotion, which ensues without a concurrent ferroelectric (180 degree) switching of the surrounding c-domain matrix. Such a mechanism could lead to ultra-low power straintronic and hybrid spintronic devices as well as domain based computing nano-architectures.


Press Coverage on our work:

On our direct measurement of ferroelectric negative capacitance (Nature Materials, 12/15/2014):

-The Center for Information Technology Research in the Interest of Society (CITRIS) at UC Berkeley: "New Discovery Opens Door For Radical Reduction in Energy Consumed by Digital Devices."

-The National Science Foundation: "New discovery opens door for radical reduction in energy consumed by digital device."

-Phys.org: "Discovery advances ferroelectrics in quest for lower power transistors."

And many more.

 

On our experimental demonstration of negative capacitance in ferroelectric-dielectric heterostructures (Appl. Phys. Lett. 9/11/2014):

-The UC Berkeley NewsCenter: "Ferroelectrics could pave way for ultra-low power computing."

-CNET.com: "New materials promise ultra-low-power computing."

-Phys.org: "Ferroelectrics could pave way for ultra-low power computing."

And many more.






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