Applied Science and Convergence Technology 2023; 32(2): 41-44
Published online March 30, 2023
Copyright © The Korean Vacuum Society.
aDepartment of Applied Physics, Sookmyung Women’s University, Seoul 04310, Republic of Korea
bInstitute of Advanced Materials and Systems, Sookmyung Women’s University, Seoul 04310, Republic of Korea
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License(http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Absolute Hall-effect sensitivity (SA) and minimum magnetic resolution (Bmin) of two-dimensional (2D) van der Waals Hall elements are predicted without magnetic fields by considering the drain voltage-dependent transconductance and current power spectrum density (PSD). The measured drain-bias-dependent PSD of rhenium disulfide multilayers is suitably described by the carrier number fluctuation noise model, indicating that the effects of carrier trapping/de-trapping into oxide traps dominate the observed current variations. To achieve high currentnormalized Hall sensitivity and SA with a low Bmin at a specific current value, the contact resistance and oxide trap density should be further optimized. Our discussion provides an effective approach for the optimization of 2D multilayer-based Hall elements.
Keywords: Two-dimensional materials, Hall sensor, Magnetic resolution, Analytical model, Contact resistance, Carrier mobility
A Hall element is a magnetic sensor that detects the presence of magnetic flux and converts this magnetic signal to a Hall voltage (
According to the conventional working principle of Hall sensors, high conductivity (or high carrier mobility at a given carrier density) with a thin material is an essential prerequisite for achieving high magnetic sensor performance [1–3]. Because of this requirement, Hall elements based on 2D van der Waals (vdW) monolayers have garnered significant interest, particularly those in graphene and molybdenum disulfide (MoS2) [1,2,7–9]. However, because the carrier mobility (or effective mass) increases (or decreases) with increasing thickness (or number of layers), 2D vdW multilayers are used as alternatives despite their greater thickness relative to monolayers. Furthermore, the feasibility of using 2D vdW multilayers has not yet been systematically investigated.
In the following section, the magnetic sensor limitations of 2D vdW multilayers for Hall elements are demonstrated. Analytical expressions for the absolute Hall-effect sensitivity (
micromechanically exfoliated ReS2 flake with a distorted octahedral (1T′) structure (purchased from a 2D semiconductor) was first transferred to a 90 nm thick SiO2/
The drain current–voltage (
Previous studies have reported that the magnetic-flux-induced
Based on the analytical definition above, the
Figure 5(a) shows the computed
Based on this final expression, the contribution of
We propose various analytical expressions for the absolute
This study was supported by an NRF grant funded by the Korean Government (MSIT) (NRF-2022R1A2C4001245). The authors also thank Minji Chae, Yeongseo Han, Dahyun Choi, and Sooyeon Kim for their assistance with the Raman and electrical measurement data collection of the 2D ReS2 multilayers.
The authors declare no competing financial interest.