Wafer‐Scale Synthesis of Graphene on Sapphire: Toward Fab‐Compatible Graphene. Issue 50 (31st October 2019) - Mishra, Neeraj
Abstract: The adoption of graphene in electronics, optoelectronics, and photonics is hindered by the difficulty in obtaining high‐quality material on technologically relevant substrates, over wafer‐scale sizes, and with metal contamination levels compatible with industrial requirements. To date, the direct growth of graphene on insulating substrates has proved to be challenging, usually requiring metal‐catalysts or yielding defective graphene. In this work, a metal‐free approach implemented in commercially available reactors to obtain high‐quality monolayer graphene on c‐plane sapphire substrates via chemical vapor deposition is demonstrated. Low energy electron diffraction, low energy electron microscopy, and scanning tunneling microscopy measurements identify the Al‐rich reconstruction 31 × 31 R ± 9 ° of sapphire to be crucial for obtaining epitaxial graphene. Raman spectroscopy and electrical transport measurements reveal high‐quality graphene with mobilities consistently above 2000 cm 2 V −1 s −1 . The process is scaled up to 4 and 6 in. wafers sizes and metal contamination levels are retrieved to be within the limits for back‐end‐of‐line integration. The growth process introduced here establishes a method for the synthesis of wafer‐scale graphene films on a technologically viable basis. Abstract : A method to synthesize wafer‐scale graphene up to 6 in. directly on sapphire without metal catalyst is demonstrated. Sapphire substrate preparation yields an aluminium‐rich reconstruction that allows to obtain graphene with carrier mobilities above 2000 cm 2 V −1 s −1 . The monitored metal contamination levels are within the limits for back‐end‐of‐line integration.