UTA Çelik-Butler Laboratory

There are two distinctly different areas of research within the group:

The research activities in Microelectromechanical Systems (MEMS) have started in early 1990s with the development of new materials for microbolometers for room temperature infrared detection. This work set the foundation for IR detectors on flexible substrates. The group demonstrated the first IR microbolometer array on a polyimide substrate with performance comparable to those on silicon substrates. Based on the success of this IR radiation detector work on flexible substrates, the group expanded to other sensing functionalities like flow, tactile, pressure, force and most recently acceleration. Integration of sensors on conformal substrates necessitated the group to initiate die-level encapsulation for flexible device packaging.

Today, the group is focusing on multifunctional, conformal sensor arrays with integrated bias, read-out and power capabilities, the so-called SMART SKIN, for aerospace, defense and medical applications.

The second thrust area is noise and reliability of nanoelectronic devices. In the early 1980s, as a graduate student under the supervision of Professor Thomas Hsiang, Dr. Çelik-Butler developed one of the first 1/f noise theories based on the McWhorter Noise Model and applied to Metal-Oxide Field-Effect Transistors (MOSFETs). Most recently, the same model has been revised to account for low-frequency noise observed on multi-stack gate MOSFETs, specifically high-k dielectric gate oxides. The research group has also investigated and developed noise models for Polysilicon Emitter Bipolar Transistors, Lateral PNP Bipolar Transistors and SiGe Heterojunction Bipolar Transistors. One of the greatest contributions of the research group is the demonstration of Random Telegraph Signal (RTS) noise as a non-destructive characterization and reliability tool in nanoelectronics.

Today, this research thrust area is investigating the effect of extended drain region on noise and reliability of LDMOS structures.

Fields of study in the Çelik-Butler Lab include:
  • MEMS packaging

    MEMS packaging has been more of a challenge than packaging of conventional semiconductor devices due to its inherent characteristics. As sensors, MEMS devices are required to be exposed to the agent(s) that they are detecting. As actuators, the geometrically complex moving parts need protection. Moreover, there might be specific requirements such as optical windows, vacuum or hermetic environments. This makes MEMS especially sensitive to damage and contamination during fabrication and packaging process.

    Many MEMS devices require a hermetic or vacuum operation environment. We are developing a post-CMOS compatible method for vacuum packaging of MEMS devices by growing an encapsulation layer during the device fabrication. The resulting MEMS devices are surrounded by a vacuum cavity and can then be placed in a conventional, low cost circuit package. This is a low temperature, area efficient, across wafer, device level encapsulation for MEMS devices.

  • Sensors

    The focus is on building multifunctional sensor arrays on flexible substrates to achieve Smart Skin. Traditional electronics utilizes stiff and thick substrates where the films on top must conform to the substrate. Any stress that develops is mainly concentrated on the film. Using compliant substrates allows the bending of devices to very small radii of curvature. As shown in the figure, if the structure is bent at a radius R, the top surface (encapsulation) is under tension and the bottom surface (substrate) is under compression. If the stiffness of the electronic layer in the middle is negligible, then the electronic layer can be made to lie on a plane of no strain.

  • Device noise reliability

    The aim of this research thrust area is to investigate the physical mechanisms behind noise and performance degradation in nanoelectronic and power electronic devices. The activities range from reliability and noise measurements under controlled degradation conditions with timed evaluation of chosen performance characteristics to analysis and modeling of the physical mechanisms causing this degradation, and eventually to prediction of device life-times.

Personnel

  • Zeynep Çelik-Butler, Ph.D., Lab Director
  • Yu Wang, Ph.D., Post-doctoral associate
  • Murali Chitteboyina, Ph.D., Post-doctoral associate

Alumni

  • Mukti Rana, Post-doctoral associate, 2007-08, (Ph.D. 2007, Electrical Engineering)
  • Vladimir Leonov, Post-doctoral associate,1998-2000
  • Petr Vasina, Post-doctoral associate, 1998
  • Lin Ren, Post-doctoral associate, 1997
  • Catherine Barros, Post-doctoral associate,1997-98
  • M. Iqbal Mahmud, Ph.D.
  • Bhargav Pradip Nabar, Ph.D.
  • Ismail Erkin Gonenli, Ph.D.
  • Suraj Kumar Patil, Ph.D.
  • Madhumita Ambokar, M.S.
  • Rohit Kilaru, M.S.
  • Md. Shahriar Rahman, Ph.D., 2009
  • Tanvir Hasan Morshed, Ph.D., 2007
  • Siva Prasad Devireddy, Ph.D., 2007
  • Bigang Min. Ph.D., 2005
  • Md. Mazhar Ul Hoque, Ph.D., 2005
  • Ali Yildiz, Ph.D., 2002
  • Alparslan Yaradanakul, Ph.D., 2002
  • Nudiatha Vibhavie Amarasinghe, Ph.D., 2001
  • Pao Chuan Shan, Ph.D., 1996
  • Wenmu He, Ph.D., 1995
  • Jiang-Lin Wang, Ph.D., 1994
  • Wiyi Yang, Ph.D., 1992
  • Sharif Alamgir, Ph.D., 1991
  • Vijaya Krishnan Ambravaneswaran, M.S., 2008
  • Vinayak Shamanna, M.S., 2005
  • Aasutosh Dave, M.S., 2005
  • Enhai Zhao, M.S., 2003
  • Fang Wang, M.S., 2000
  • John E. Gray, M.S., 1998
  • Agha Jahanzeb, M.S., 1995

Patents

  • "Uncooled YBaCuO Thin Film Infrared Detector," by Donald P. Butler, Zeynep Çelik-Butler, and Pao Chuan Shan. 1996. Patent #: 5572060.
  • "Amorphous YBaCuO Thin Film Infrared Bolometer for Uncooled Infrared Detection," by Donald P. Butler, Zeynep Çelik-Butler, Pao Chuan Shan, and Agha Jahanzeb. 1998. Patent #: 5821598.
  • "Uncooled YBaCuO Thin Film Infrared Detector (Divisional Application for Pyroelectric Effect)," by Donald P. Butler, Zeynep Çelik-Butler, and Pao Chuan Shan. 1997. Patent #: 5672903.
  • "Uncooled Amorphous YBaCuO Thin Film Infrared Detection," by Donald P. Butler, Zeynep Çelik-Butler, Pao Chuan Shan, and Agha Jahanzeb. 1998. Patent #: 5850098.
  • "A Cardiopulmonary Resuscitation Sensor," by Zeynep Çelik-Butler, John W. Priest, Carolyn Cason, Mary E. Mancini, Kenneth E. Morallee, Helge Fossan, Filed on June 15, 2007. Patent Application No. 11764174.
  • "Micromachined Nanoporous Membrane Blood Oxygenator," by Zeynep Çelik-Butler, Richard Billo, Robert C. Eberhart, Cheng-Jen Chuong, Richard Timmons, Vijayakrishnan Ambravaneswaran. Filed on October 16, 2007. Patent Application No. 11873142
  • “A Thin Flexible Sensor,” by Zeynep Çelik-Butler and Donald P. Butler, Full patent application May 2008. Patent Application No. 60944479.
  • “Method and Apparatus for Fabricating Piezoresistors by Aluminum Induced Crystallization,” Z. Çelik-Butler, Suraj K. Patil and Donald P. Butler, Filed on August 14, 2008. Patent Application No. 61/088,820.
  • “Method, Apparatus, and Compositions for Packaging RF MEMS,” Z. Çelik-Butler, D. P. Butler, M. Chitteboyina and M. S. Rahman, Filed on June 17, 2009. Provisional Application No. 61218032

Publications