(Invited) Integrated Crystal Growth of 2D Materials

Abstract

In order to serve the industrial demand for “electronic-grade” 2D materials, we focus on chemical vapour deposition (CVD), and in this talk I will review our recent progress in scalable CVD [1] and device integration approaches of highly crystalline graphene and hexagonal boron nitride (h-BN) films. The systematic use of in-situ metrology, ranging from high-pressure XPS to environmental electron microscopy, allows us to reveal some of the key mechanisms that dictate crystal phase, structural, defect, interfacial and heterogeneous integration control at industrially relevant conditions [2,3]. We systematically also explored the parameter space of atomic layer deposition (ALD) of oxides on graphene to achieve ultrathin continuous AlOx films directly on graphene [4]. These results have model system character for rational 2D/non-2D material process integration [5]. We highlight how the interplay between the 2D material and the catalyst is not only important for growth [6] but also decisive for transfer processes and show how intercalation processes allow for instance local Cu oxidation at the interface followed by selective oxide dissolution, which gently releases the 2D material [7]. We developed direct and transfer 2D material integration approaches for a large number of diverse applications, ranging from spintronics [8], to nanopore sensing [9] and THz devices [10]. Crystal growth and processing of these 2D materials reached a level where detailed, adequate characterisation over large areas has become a key challenge. Hence we also study new non-contact characterisation methods for rapid in-line monitoring [11]. References Hofmann et al., J. Phys. Chem. Lett. 6, 2714 (2015).Weatherup et al., Nano Lett. 16, 6196 (2016).Caneva et al. Nano Lett. 16, 1250 (2016).Aria et al. ACS Appl. Mater. Interfaces 8, 30564 (2016).Alexander-Webber et al., 2D Mater. 4, 011008 (2016).Braeuninger-Weimar et al., Chem. Mater. 28, 8905 (2016).Wang et al., ACS Appl. Mater. Interfaces 8, 33072 (2016).Piquemal-Banci et al., Appl. Phys. Lett. 108, 102404 (2016).Walker et al., ACS Nano 11, 1340 (2017).Degl’Innocenti et al., ACS Photonics 3, 1747 (2016).Lin et al. Sci. Rep. 7, 10625 (2017).