Robert R. Mallik, Ph.D.
Title: Professor
Dept/Program: Physics
Office: Crouse Hall 334
Phone: 330-972-7145
Fax: 330-972-6918
Email: mallik@uakron.edu
Research
Research in my group focuses primarily on surface science. In particular, we are interested in the preparation and characterization of nanoscale thin films, layered structures, and the interfaces between the layers. There are many applications for such structures, for example, thin-film electronic devices, sensors, and photovoltaic heterojunctions.
My work has been funded by various external agencies including the Air Force Office of Scientific Research, Alcoa, Cornell University, Goodyear Tire and Rubber Company, Federal Mogul Corporation, the John Fluke Company, Mattson Instruments Inc., the National Science Foundation, the Ohio Board of Regents, and Research Corporation.
Over the last few years, the research has been centered on ultra-thin sputtered amorphous semiconductor films including CdS, CdTe, and silicon. Some of the goals of the work are to identify:
- how charge is transported through the films,
- how, where, and what defects are formed at or near the surface of the films (minimization of such defects is crucial to improving efficiency of charge transport),
- how molecules adsorb and, in some cases, self-assemble on the films,
- how the presence of adsorbed layers affects the electronic and optical properties of the films.
A key component in characterizing the films is vibrational spectroscopy. We use two primary techniques: Inelastic Electron Tunnelling Spectroscopy (IETS) and Multiple Reflection Absorption Infrared Spectroscopy (MRAIRS). We collaborate with colleagues in other °µºÚ±¬ÁÏ departments on Surface Enhanced Raman Spectroscopy (SERS). Used in conjunction, these techniques used allow us to identify not only the chemical composition of the films and interfaces, but also the orientation and bonding mechanisms of adsorbed molecules. We also use Atomic Force Microscopy (AFM) for topological characterization and nanoscale patterning (see below).
Some of our recent work has been the investigation of conductivity enhancement in CdS based heterojunctions. We have fabricated heterojunctions incorporating a new, patented adamantane-anchor based compound developed by colleagues in the chemistry department. The compound is used to produce the SAM layer which is spin coated onto ultrathin (~3 nm) sputtered a-CdS films. Analysis of Conductance-Voltage (G,V) data for the heterojunctions over a wide temperature range (4.2 K to room temperature) indicates that the dominant conduction mechanisms, depending on the various (G,V,T) regimes, are tunneling and a surface-state mediated mechanism due to coupling between the SAM and the CdS surface. We have also shown that the introduction of the SAM layer significantly enhances the conductivity of the heterojunction; this opens up the possibility for the investigation of related SAMs for further conductivity enhancement and makes a case for the SAMs as candidates for use in molecular electronic devices.
Our group also collaborates closely with Professor Lyuksyutov’s on research and we were funded by °µºÚ±¬ÁÏ’s Polymer Photonics Center. We have used a robust patterning technique, developed by Professor Lyuksyutov’s group, to create raised nanostructures on semiconductor and polymer films. Professor Lyuksyutov’s technique, z-lift Amplitude Modulated Atomic Force Microscopy Assisted Electrostatic Nanolithography (ZAM), allows the surface of the films to be geometrically functionalized by the vertical manipulation of a negatively biased oscillating Atomic Force Microscope (AFM) cantilever. We have shown ZAM to be capable of functionalizing the surface morphology of amorphous CdS, a variety of polymers, and styrene butadiene rubber (SBR) at room temperature. The latter represents the first reported cross-linking at the nanoscale. The technique has potential for the functionalization of other materials and organic photovoltaic devices.
Research is inextricably linked with teaching, and participation in research greatly helps students in establishing the interconnections between various branches of physics. I urge students to participate in research as soon as possible and actively involve them in projects from the introductory undergraduate level through to the PhD. I have directed 12 undergraduate research projects, 14 MS projects, and 2 PhD (as part of °µºÚ±¬ÁÏ’s Chemical Physics program). I have also worked with high school students on projects. I am currently the advisor to, 3 MS and 1 BS research students. If you are a current or future student at °µºÚ±¬ÁÏ interested in participating in our research, please contact me -- I would be happy to arrange a tour of our facilities for you.
Publications
"Investigation of Thermally Grown Copper Oxides with Inelastic Electron Tunnelling Spectroscopy", R.D. Ramsier, R.R. Mallik, and P.N. Henriksen, J. Appl. Phys. 66(9), 4539 (1989).
"Inelastic Electron Tunnelling Spectroscopic Studies of Alkoxysilanes Adsorbed on Alumina", P.N. Henriksen, R.R. Mallik, and R.D. Ramsier, J. Adhesion Sci. Technol. 5(4), 321 (1991).
"Inelastic Electron Tunnelling Spectroscopy of Amorphous SiOx Barriers", R.R. Mallik, W.J. Kulnis, Jr., and T. Butler, Jr., J. Appl. Phys. 70(7), 3703 (1991).
"Characterization of Ultrathin Sputtered SiO Films on Alumina by Inelastic Electron Tunnelling Spectroscopy and Atomic Force Microscopy", R. R. Mallik, T. Butler, Jr., W. J. Kulnis, Jr., T. S. Confer, and P. N. Henriksen, J. Vac. Sci. technol. A 10(4), 2412 (1992).
"Inelastic Electron Tunneling Spectroscopy and Atomic Force Microscopy Investigation of Ultrathin Sputtered Amorphous Silica Films on Gold", R. R. Mallik, W. J. Kulnis, Jr., T. Butler, Jr., and B. DeVier, J. Appl. Phys. 73(5), 2347 (1993).
"An Easily Realized Inelastic Electron Tunnelling Spectrometer", Y. Wang, R.R. Mallik, and P.N. Henriksen, Rev. Sci. Instruments. 64(4), 890 (1993).
"Crystallographic Structure and Defects in Epitaxial Bismuth Films grown on Mica", J.Jing, H. Wang, R.R. Mallik, P.N. Henriksen, and H.T. Chu, J. Crystal Growth 130, 571 (1993).
"Production and Separation of C60 and C70 as an Undergraduate Experiment", D.S. Bradley, J.L. Massey, R.R. Mallik, and P.N. Henriksen, American Journal of Physics 62(1), 85 (1994).
"Comparison of the Vibrational Spectra of Pyruvic Acid on Alumina using Inelastic Electron Tunneling Spectroscopy and Fourier Transform Infrared Spectroscopy", S. Devdas, R.R. Mallik, R. Coast, and P.N. Henriksen, Surface Science 326, 327 (1995).
"Inelastic Electron Tunneling Spectroscopy of Trigethoxysilane on Germania, a Model Study for Silane-Glass Adhesion", R.R Mallik, S. Anabtawi, B. Moore, and T.A. Hartman, Surface Science 380, 124-130 (1997).
"Electronic Signal regulator for Constant Resolution Inelastic Electron Tunneling Spectroscopy", T.R. Seman, and R.R. Mallik, Rev. Sci. Instruments 70 (6), 2808, (1999)
Education
- •B.S., Joint Honours in Physics and Mathematics - Leicester Polytechnic, England - 1981.
- •Ph.D., Applied Physics - Leicester Polytechnic, England - 1985.
- •Post Doctoral Researcher - University of Akron - 1985 - 1986.
- •Post-Doctoral Fellow, Cavendish Laboratory, University of Cambridge, England,1986 - 1988.
- •Supervisor, Natural Science Tripos (Physics), Queens' College, University of Cambridge, 1986-1988.
- •Assistant Professor, Department of Physics, University of Akron, 1988-1992.
- •Associate Professor, Department of Physics and Department of Chemistry, University of Akron, 1993-2000.
- •Professor, Department of Physics and Department of Chemistry, University of Akron, 2000-present.
- •Professor and Chair, Department of Physics, University of Akron, Akron Ohio, 2000-2012.
- Research Interests