(Invited) Controlling and Tailoring the Electronic Properties of Chemically Reactive 2D Materials

Abstract

Following the success of ambient-stable two-dimensional (2D) materials such as graphene and hexagonal boron nitride (hBN), new classes of chemically reactive layered solids are being explored since their unique electronic and optical properties hold significant promise for improved device performance [1]. For example, chemically reactive 2D semiconductors such as black phosphorus (BP) and indium selenide (InSe) have shown significantly enhanced field-effect mobilities under controlled conditions that minimize ambient degradation [2]. In addition, 2D boron (i.e., borophene) is an anisotropic metal with a diverse range of theoretically predicted phenomena including confined plasmons, charge density waves, and superconductivity [3], although its high chemical reactivity has limited experimental studies to inert ultrahigh vacuum conditions [4-6]. Therefore, to fully study and exploit the vast majority of 2D materials, methods for mitigating or exploiting their relatively high chemical reactivity are required [7]. This talk will thus explore recent efforts to control and tailor the electronic properties of chemically reactive 2D materials [8]. In particular, covalent organic functionalization of black phosphorus minimizes ambient degradation, provides charge transfer doping, and enhances field-effect transistor mobility and on/off ratio [9]. In contrast, noncovalent organic functionalization of borophene leads to the spontaneous formation of electronically abrupt lateral organic-borophene heterostructures [10]. Finally, atomic layer deposition (ALD) encapsulation schemes will be discussed that impart ambient stability to high-performance black phosphorus infrared optical emitters [11] and InSe photodetectors [12]. [1] A. J. Mannix, et al., Nature Reviews Chemistry, 1, 0014 (2017). [2] D. Jariwala, et al., Nature Materials, 16, 170 (2017). [3] A. J. Mannix, et al., Nature Nanotechnology, 13, 444 (2018). [4] A. J. Mannix, et al., Science, 350, 1513 (2015). [5] G. P. Campbell, et al., Nano Letters, 18, 2816 (2018). [6] X. Liu, et al., Nature Materials, 17, 783 (2018). [7] C. R. Ryder, et al., ACS Nano, 10, 3900 (2016). [8] X. Liu, et al., Advanced Materials, 30, 1801586 (2018). [9] C. R. Ryder, et al., Nature Chemistry, 8, 597 (2016). [10] X. Liu, et al., Science Advances, 3, e1602356 (2017). [11] C. Husko, et al., Nano Letters, 18, 6515 (2018). [12] S. A. Wells, et al., Nano Letters, DOI: 10.1021/acs.nanolett.8b03689 (2018).