Apr 9, 2025
8:30am - 9:00am
Summit, Level 3, Room 345
Mark Hersam1
Northwestern University1
The experimental realization of two-dimensional (2D) boron – i.e., ‘borophene’ – has spurred broad interest in its unique material attributes such as in-plane anisotropy, seamless phase intermixing, high mechanical strength and flexibility, massless Dirac fermions, and phonon-mediated superconductivity. The polymorphic nature of borophene, which is rooted in the rich bonding configurations among boron atoms, further distinguishes it from other 2D materials and offers an additional means for tailoring its material properties [1]. This presentation will explore the ultrahigh vacuum synthesis and atomic-scale scanning probe microscopy characterization of borophene on noble metal substrates. In addition to distinct borophene polymorphs, conditions for forming borophene superlattices [2], bilayers [3], and nanoribbons [4] will be delineated. Using field emission resonance spectroscopy [5], tip-enhanced Raman spectroscopy [6], and inelastic electron tunneling spectroscopy [7], electronic and vibrational properties can be quantified, revealing subtle differences between the different borophene phases. By exploiting spatially inhomogeneous surface chemistry, seamless 2D heterointerfaces can also be realized between borophene and other materials including organic semiconductors, graphene, and graphene nanoribbons, each of which show atomically sharp electronic interfaces as confirmed by scanning tunneling microscopy and spectroscopy [8]. In an effort to further tune the chemical and electronic properties of 2D boron, covalent hydrogenation of borophene has been achieved, resulting in a series of ‘borophane’ polymorphs that possess significantly higher stability in ambient conditions compared to pristine borophene [9]. Overall, this work establishes a series of design rules for manipulating and integrating 2D boron into a range of next-generation electronic and quantum technologies.
[1] H. Bergeron,
et al.,
Chemical Reviews,
121, 2713 (2021).
[2] L. Liu,
et al.,
Nano Letters,
20, 1315 (2020).
[3] X. Liu,
et al.,
Nature Materials,
21, 35 (2022).
[4] Q. Li,
et al.,
ACS Nano,
18, 483 (2024).
[5] X. Liu,
et al.,
Nano Letters,
21, 1169 (2021).
[6] L. Li,
et al.,
Angew. Chem. Int. Ed.,
62, e202306590 (2023).
[7] H. Li,
et al.,
Nano Letters,
24, 10674 (2024).
[8] Q. Li,
et al.,
Nano Letters,
21, 4029 (2021).
[9] Q. Li,
et al.,
Science,
371, 1143 (2021).