Exploring Alternative Layered Materials as Gate Dielectrics for 2D Material Based Devices

The performance and scalability of two-dimensional (2D) based quantum devices are strongly influenced by the choice of gate dielectric. In gate-defined quantum devices high-κ dielectrics improve electrostatic tunability, and reduce gate leakage. Hexagonal boron nitride (hBN), a 2D layered material, has become a widely used dielectric due to the clean interface it forms with 2D materials and its wide band gap. However, its relatively low dielectric constant (κ ≈ 2.5–4) [1] limits the gate capacitance, and incidentally the charge carrier density.

This project aims to explore Lanthanum OxyBromide (LaOBr) as an alternative crystalline layered dielectric. Its properties such as a high dielectric constant, large band gap, and its compatibility with van der Waals heterostructures [2] makes it a promising material to overcome the limitations of hBN while preserving the benefits of a 2D-2D interface.

To evaluate LaOBr as a suitable gate dielectric, we fabricated 2D-based field-effect devices and characterized key electrical properties, focusing on the gate leakage current, device carrier mobility, gate dielectric breakdown, and dielectric constant. This work will prompt the study of other layered high k dielectrics as alternatives to hBN, providing additional tuning knobs for heterostructure fabrication.

References:

1. [1] J. Boddison-Chouinard, et al. npj 2D Mater Appl 7, 50 (2023)
   
   [2] A. Soll et al ACS Nano 2024, 18, 15, 10397–10406 (2024)