EECS500 Fall 2012 Department Seminar

Anirudhu Sumant
Diamond thin films: A new platform for developing high performance electronic devices
Argonne National Laboratory
White Bldg., Room 411
11:30am - 12:30pm
October 9, 2012

     A continuous trend towards device miniaturization for developing high-density, high power electronics is facing enormous challenge of overcoming heat dissipation. Reduced length scale and confined device geometries are putting additional constrains on removing heat effectively from integrated circuits and therefore there is an immediate need for fundamental change in the device architecture to solve this problem. Diamond is well-known for its highest thermal conductivity among other excellent materials properties. However, higher deposition temperature (~800oC), high as-grown roughness (~50 nm) and economic viability of synthesizing diamond thin films over large area restricted the use of diamond as a heat-sink in electronic devices. Current progress in chemical vapor deposition of diamond thin films has overcome most of these problems [1-2]. We have recently demonstrated synthesis of diamond films at 400 oC and enhancement in the device performance fabricated on diamond by tuning the surface roughness and thermal conductivity of the diamond film, which has opened-up new possibilities of exploring diamond thin films as a platform for developing active electronic devices.
     In this talk, I will discuss two new technologies that we have developed viz. Graphene-on-diamond [3] and GaN-on-diamond [4] respectively. In the first case, we show for the first time that by the use of thin ultrananocrystalline diamond thin films on silicon in graphene-on-diamond configuration, the heat dissipation can be improved substantially improving the breakdown current density in graphene up to 50% as compared to conventional graphene-on-SiO2 substrates. We also demonstrate the fabrication of first top gated graphene-on- diamond devices and discuss their performance. The obtained devices had the carrier mobility ~ 2590 cm2V-1S-1 for holes and ~1520 cm2V-1S-1 for electrons. We further demonstrate that the breakdown current density of few layer graphene device fabricated on the single crystal diamond could be increased to 109 A/cm2, which is highest reported to date.  In the second case, we demonstrate direct integration of nanocrystalline diamond thin film with GaN substrate at low substrate temperature. This approach allowed seamless integration of diamond with GaN without degrading the intrinsic electronic and structural properties of GaN as well as better heat removal from the GaN substrate. The obtained results are promising in terms of developing future energy efficient, high performance, and high-power electronic devices and interconnections.  References: A. V. Sumant et al. MRS Bulletin, 35(4), 281 (2010). A. V. Sumant et al. Materials Today, 15(9), 358 (2012). J. Yu et al. Nano Letters, 12(3), 1603 (2012). V. Goyal et al. Advanced Functional Materials, 22(7), 1525 (2012),


Anirudha Sumant is a Materials Scientist at Center for Nanoscale Materials, Argonne National Laboratory. He has over 15 years of research experience in the synthesis, characterization and processing of carbon based materials including CVD-diamond thin films, diamond-like carbon, carbon nanotubes, and recently graphene. His main research interests include understanding nucleation and growth mechanism of diamond thin film, surface chemistry of diamond surfaces, micro- and nanoscale tribology, and their impact on the performance of both microelectromechanical systems (MEMS) and NEMS devices based on diamond. He has authored and co-authored over 75 research publications including some of them in high impact journals such as Science, Physical Review Letters, Nano Letters, and Advanced Materials. He has 1 issued US patent and 10 pending. He is also a recipient of R&D award in 2011 for his work on the development of CMOS compatible RF-MEMS switch technology based on diamond. His research work in the area of nanocrystalline diamond thin films has inspired formation of two start-up companies such as NCD Technologies Inc. and Advanced Diamond Technologies Inc. He is an active member of MRS and AVS and he has been serving as a Group Chair for the MEMS and NEMS Technical Group at AVS from last 6 years.