Highly Stable and Effective Doping of Graphene by Selective Atomic Layer Deposition of Ruthenium

Abstract

The sheet resistance of graphene synthesized by chemical vapor deposition is found to be significantly reduced by the selective atomic layer deposition (ALD) of Ru onto defect sites such as wrinkles and grain boundaries. With 200 ALD cycles, the sheet resistance is reduced from similar to 500 to <50 Omega/sq, and the p-type carrier density is drastically increased from 10(13) to 10(15) cm(-2). At the same time, the carrier mobility is reduced from similar to 670 to less than 100 cm(2) V-1 s(-1). This, doping of graphene proved to be very stable, with the electrical properties remaining unchanged over eight weeks of measurement. Selective deposition of Ru on defect sites also makes it possible to obtain a grapherie film that is both highly transparent and electrically conductive (e.g., a sheet resistance of 125 Omega/sq with 92% optical transmittance at 550 nm). Highly doped graphene layers achieved by Ru ALP are therefore expected to provide a-viable basis for transparent conducting electrodes.