2D metallic transition metal dichalcogenides: promising contact metals for 2D GaN-based (opto)electronic devices†

IF 2.9 3区 化学 Q3 CHEMISTRY, PHYSICAL
Jing Li, Lei Ao and Zhihua Xiong
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引用次数: 0

Abstract

Owing to their high light absorption coefficient, excellent electronic mobility, and enhanced excitonic effect, two-dimensional (2D) GaN materials hold great potential for applications in optoelectronic and electronic devices. As the metal–semiconductor junction (MSJ) is a fundamental component of semiconductor-based devices, identifying a suitable metal for contacting semiconductors is essential. In this work, detailed first-principles calculations were performed to investigate the contact behavior between the GaN monolayer (ML) and a series of 2D metals MX2 (M = Nb, Ta, V, Mo, or W; X = S or Se). Despite the van der Waals (vdW) interface, the Schottky barrier heights (SBHs) of the MX2/GaN MSJs were found to deviate significantly from the Schottky–Mott limit. Stronger and weaker Fermi level pinning effects were identified in the higher and lower work function (WM) regions of the metals, respectively. This was attributed to the asymmetric charge redistribution-induced enhanced interface dipole (ΔP) in MSJs, leading to an increased step potential (ΔV) as response to the increased WM of MX2. p-Type quasi-ohmic contact could be realized in Ga-top stacking H-TaS2/GaN, H-NbS2/GaN, and H-VS2/GaN, indicating the potential application of 2D H-TaS2, H-NbS2, and H-VS2 as electrode materials. Applying biaxial tensile strain was identified as a feasible strategy for modulating the contact behavior in MX2/GaN, as it could effectively tune the SBH, change the contact type, or induce a transition from Schottky to quasi-ohmic contact. We demonstrated that strain effects on the contact properties of MX2/GaN MSJs were both MX2 and stacking configuration dependent, which were determined by the synergistic effect of the strain-modulated ionization energy and electron affinity of GaN ML, the WM of MX2, and the ΔV- and ΔP-quantified interface coupling in MSJs. Our work not only offers insights into the fundamental contact properties of 2D metal/GaN vdW interfaces but also provides strategies for electrode material selection and strain engineering to achieve ohmic contact and tunable SBHs in 2D GaN. This helps to provide theoretical guidance for the development of high-performance 2D GaN-based optoelectronic and electronic devices.

Abstract Image

二维金属过渡金属二硫族化合物:二维氮化镓基(光电)电子器件的有前途的接触金属
由于高的光吸收系数、优异的电子迁移率和增强的激子效应,二维(2D) GaN材料在光电和电子器件中具有很大的应用潜力。金属-半导体结(MSJ)是半导体器件的基本组成部分,因此确定与半导体接触的合适金属是至关重要的。在这项工作中,进行了详细的第一性原理计算来研究GaN单层(ML)与一系列二维金属MX2 (M = Nb, Ta, V, Mo或W;X = S或Se)。尽管存在范德华(vdW)界面,但MX2/GaN MSJs的Schottky势垒高度(SBHs)明显偏离Schottky - mott极限。在金属的高功函数区和低功函数区分别确定了较强和较弱的费米能级钉钉效应。这是由于不对称电荷重分配导致MSJs中界面偶极子(ΔP)增强,导致阶跃电位(ΔV)随着MX2的WM增加而增加。在ga顶部叠加H-TaS2/GaN、H-NbS2/GaN和H-VS2/GaN中可以实现p型准欧姆接触,表明二维H-TaS2、H-NbS2和H-VS2作为电极材料具有潜在的应用前景。应用双轴拉伸应变是调制MX2/GaN中接触行为的可行策略,因为它可以有效地调节SBH,改变接触类型或诱导肖特基到准欧姆接触转变。研究表明,应变对MX2/GaN MSJs接触性能的影响取决于MX2和堆叠构型,这是由GaN ML的应变调制电离能和电子亲和、MX2的WM以及MSJs中ΔV-和ΔP-quantified界面耦合的协同效应决定的。我们的工作不仅为探索二维金属/GaN vdW界面的基本接触特性提供了见解,而且还提供了在二维GaN中实现欧姆接触和可调谐SBHs的电极材料选择和应变策略,这有助于为开发高性能的二维GaN光电和电子器件提供理论指导。
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来源期刊
Physical Chemistry Chemical Physics
Physical Chemistry Chemical Physics 化学-物理:原子、分子和化学物理
CiteScore
5.50
自引率
9.10%
发文量
2675
审稿时长
2.0 months
期刊介绍: Physical Chemistry Chemical Physics (PCCP) is an international journal co-owned by 19 physical chemistry and physics societies from around the world. This journal publishes original, cutting-edge research in physical chemistry, chemical physics and biophysical chemistry. To be suitable for publication in PCCP, articles must include significant innovation and/or insight into physical chemistry; this is the most important criterion that reviewers and Editors will judge against when evaluating submissions. The journal has a broad scope and welcomes contributions spanning experiment, theory, computation and data science. Topical coverage includes spectroscopy, dynamics, kinetics, statistical mechanics, thermodynamics, electrochemistry, catalysis, surface science, quantum mechanics, quantum computing and machine learning. Interdisciplinary research areas such as polymers and soft matter, materials, nanoscience, energy, surfaces/interfaces, and biophysical chemistry are welcomed if they demonstrate significant innovation and/or insight into physical chemistry. Joined experimental/theoretical studies are particularly appreciated when complementary and based on up-to-date approaches.
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