Ultrathin natural biotite crystals as a dielectric layer for van der Waals heterostructure applications

Author(s)

de Oliveira, Raphaela ; Yoshida, Ana B. Barbosa ; Rabahi, Cesar R. ; Freitas, Raul ; Teixeira, Veronica C. ; de Matos, Christiano J. S. ; Gobato, Yara Galvao ; Barcelos, Ingrid D. ; Cadore, Alisson R.

• Document type: Journal article
• Source: Nanotechnology; v. 35, n. 50, p. 11-pg., 2024-12-09.

Abstract

Biotite, an iron-rich mineral belonging to the trioctahedral mica group, is a naturally abundant layered material (LM) exhibiting attractive electronic properties for application in nanodevices. Biotite stands out as a non-degradable LM under ambient conditions, featuring high-quality basal cleavage-a significant advantage for van der Waals heterostructure (vdWH) applications. In this work, we present the micro-mechanical exfoliation of biotite down to monolayers (1Ls), yielding ultrathin flakes with large areas and atomically flat surfaces. To identify and characterize the mineral, we conducted a multi-elemental analysis of biotite using energy-dispersive spectroscopy mapping. Additionally, synchrotron x-ray fluorescence and infrared nano-spectroscopy were employed to probe its iron content and vibrational signature in few-layer form, respectively, with sensitivity to the layer number. We have also observed good morphological and structural stability in time (up to 12 months) and no important changes in their physical properties after thermal annealing processes in ultrathin biotite flakes. Conductive atomic force microscopy evaluated its electrical capacity, revealing an electrical breakdown strength of approximately 1 V nm-1. Finally, we explore the use of biotite as a substrate and encapsulating LM in vdWH applications. We have performed optical and magneto-optical measurements at low temperatures. We find that ultrathin biotite flakes work as a good substrate for 1L-MoSe2, comparable to hexagonal boron nitride flakes, but it induces a small change of the 1L-MoSe2 g-factor values, most likely due to natural impurities on its crystal structure. Furthermore, our results show that biotite flakes are useful systems to protect sensitive LMs such as black phosphorus from degradation for up to 60 days in ambient air. Our study introduces biotite as a promising, cost-effective LM for the advancement of future ultrathin nanotechnologies. (AU)

• FAPESP's process: 15/13771-0 - Multi-User Equipment approved in grant 14/19142-2: ultra-low vibration cryostat with magnetic field and confocal microscope
• Grantee: Gilmar Eugenio Marques
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 19/14017-9 - From excitons waves to THz-phonons: 2Ds materials nano-optics via synchrotron infrared nanospectroscopy
• Grantee: Raul de Oliveira Freitas
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 22/11526-2 - Scientific MUE: acquisition of a 100 kV electron beam nanolithography system for high-throughput and high-precision devices fabrication
• Grantee: Newton Cesario Frateschi
• Support Opportunities: Research Infrastructure Program - Scientific
• FAPESP's process: 14/07375-2 - Multi-user equipment approved in grant 2013/18719-1: time resolved measurement system
• Grantee: Marcio Daldin Teodoro
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 22/08329-0 - Effect of Moiré pattern on physical properties of twisted van der Waals heterostructures
• Grantee: Yara Galvão Gobato
• Support Opportunities: Regular Research Grants
• FAPESP's process: 22/10340-2 - Scientific MUE: acquisition of a high temporal, spatial and spectral resolution fluorescence system operating over a wide temperature range
• Grantee: Gilmar Eugenio Marques
• Support Opportunities: Research Infrastructure Program - Scientific
• FAPESP's process: 22/02901-4 - Nano-optics of polaritons in two-dimensional crystals and at the metal/dielectric interface in the mid-to-far infrared
• Grantee: Francisco Carlos Barbosa Maia
• Support Opportunities: Research Grants - Initial Project