arXiv subjects

Yujin Ji

Publications and source records attributed to Yujin Ji.

3 recordsLinked to original sources

arXiv2025

Rational Design of Two-Dimensional Octuple-Atomic-Layer M2A2Z4 for Photocatalytic Water Splitting

Two-dimensional (2D) materials have emerged as promising candidates as photocatalytic materials due to their large surface areas and tunable electronic properties. In this work, we systematically design and screen a series of octuple-atomic-layer M2A2Z4 monolayers (M = Al, Ga, In; A = Si, Ge, Sn; Z = N, P, As) using first-principles calculations. 108 structures are constructed by intercalation approach, followed by a comprehensive evaluation of their thermodynamic and dynamic stability, band gaps, and band edge alignments to assess their potential for photocatalytic overall water splitting. Eight candidates meet the criteria for overall water splitting, among which Al2Si2N4 and Al2Ge2N4 exhibit suitable band edge positions, pronounced visible-light absorption, high electron mobility and high solar-to-hydrogen (STH) efficiencies for photocatalysis under both acidic and neutral environments (pH = 0 and 7). Importantly, the introduction of N vacancies on the surfaces of Al2Si2N4 and Al2Ge2N4 significantly enhances their catalytic activity for both hydrogen reduction and water oxidation reactions, further supporting their potential as photocatalysts for overall water splitting. Both materials also display robust structural stability in aqueous environments. Our study provides theoretical insights for the rational design of efficient and stable 2D photocatalysts for overall water splitting.

cond-mat.mtrl-sci↗

arXiv2024

A Metastable Pentagonal 2D Material Synthesized by Symmetry-Driven Epitaxy

Most two-dimensional (2D) materials experimentally studied so far have hexagons as their building blocks. Only a few exceptions, such as PdSe2, are lower in energy in pentagonal phases and exhibit pentagons as building blocks. While theory has predicted a large number of pentagonal 2D materials, many of them are metastable and their experimental realization is difficult. Here we report the successful synthesis of a metastable pentagonal 2D material, the monolayer pentagonal PdTe2, by symmetry-driven epitaxy. Scanning tunneling microscopy and complementary spectroscopy measurements are used to characterize the monolayer pentagonal PdTe2, which demonstrates well-ordered low-symmetry atomic arrangements and is stabilized by lattice matching with the underlying Pd(100) substrate. Theoretical calculations, along with angle-resolved photoemission spectroscopy, reveal monolayer pentagonal PdTe2 is a semiconductor with an indirect bandgap of 1.05 eV. Our work opens an avenue for the synthesis of pentagon-based 2D materials and gives opportunities to explore their applications such as multifunctional nanoelectronics.

cond-mat.mtrl-sci↗

arXiv2019

Enhancing Interconnect Reliability and Performance by Converting Tantalum to 2D Layered Tantalum Sulfide at Low Temperature

The interconnect half-pitch size will reach ~20 nm in the coming sub-5 nm technology node. Meanwhile, the TaN/Ta (barrier/liner) bilayer stack has to be > 4 nm to ensure acceptable liner and diffusion barrier properties. Since TaN/Ta occupy a significant portion of the interconnect cross-section and they are much more resistive than Cu, the effective conductance of an ultra-scaled interconnect will be compromised by the thick bilayer. Therefore, two dimensional (2D) layered materials have been explored as diffusion barrier alternatives. However, many of the proposed 2D barriers are prepared at too high temperatures to be compatible with the back-end-of-line (BEOL) technology. In addition, as important as the diffusion barrier properties, the liner properties of 2D materials must be evaluated, which has not yet been pursued. Here, a 2D layered tantalum sulfide (TaSx) with ~1.5 nm thickness is developed to replace the conventional TaN/Ta bilayer. The TaSx ultra-thin film is industry-friendly, BEOL-compatible, and can be directly prepared on dielectrics. Our results show superior barrier/liner properties of TaSx compared to the TaN/Ta bilayer. This single-stack material, serving as both a liner and a barrier, will enable continued scaling of interconnects beyond 5 nm node.

cond-mat.mtrl-sci↗