An ultra-thin top-gate dielectric is essential for high-performance large-scale digital and analog electronics based on graphene field-effect transistors (G-FETs). Atomic layer deposition (ALD) has been utilized to grown top-gate dielectrics for high-performance G-FETs. However, ALD requires a seeding layer – often up to 10 nm thick – on the chemically inert graphene surface. Moreover, large-area uniformity and reliability of top-gate dielectrics have not yet been characterized. Here, we show that a single monolayer of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) film can serve as a robust seeding layer for 8 nm thick Al2 O3 as the top-gate dielectric in G-FETs with mobilities up to 3000 cm^2/Vs. For the first time, we address the issue of large-area uniformity by conducting an industry-standard statistical analysis of top-gate dielectric breakdown. To this end, metal-insulator-semiconductor (MIS) capacitors (area = 20 µm x 20 µm) were fabricated on 10 nm thick Al2 O3 over a 0.9 cm x 0.45 cm area of epitaxial graphene grown on n-doped SiC substrates. As expected for an ultra-thin dielectric, we observe that the distribution of breakdown voltage fits well to a Weibull distribution. The dielectric breakdown is characterized by a sudden catastrophic rise in current. The shape parameter (indicating distribution width) and scale parameter (where 63% devices fail) of the distribution are calculated to be 37.64 confidence bounds 31.59-44.84 and 8.92 V confidence bounds 8.86-8.98, respectively, from measurements of 70 capacitors. Overall, this study of dielectric breakdown highlights the critical issue of device reliability that will become increasingly important as graphene moves from research laboratories to commercial applications.
I am currently a postdoctoral researcher in Materials Science and Engineering department in Northwestern University. I work with Prof Mark Hersam, Prof. Lincoln Lauhon and Prof. Tobin Marks research groups. I did Ph.D. in the Department of Physics with Prof Ellen Williams and Prof Michael Fuhrer from University of Maryland, College Park. Before that I obtained B.Tech. degree in Engineering Physics from Indian Institute of Technology, Mumbai, India. Source
Vinod K. Sangwan, Deep Jariwala, Stephen A. Filippone, Hunter J. Karmel, James E. Johns, Justice M.P. Alaboson, Tobin J. Marks, Lincoln J. Lauhon, Mark C. Hersam
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University of Illinois Urbana-Champaign, Urbana, IL