1 Versatile van der Waals Heterostructures of γ-GeSe with h- BNGraphene MoS 2

2025-04-30 0 0 2.44MB 27 页 10玖币

侵权投诉

Versatile van der Waals Heterostructures of γ-GeSe with h-

BN/Graphene/MoS2

Changmeng Huan1,2, Pu Wang1,2, Bingtao Liu1,2, Binghan He1,2, Yongqing Cai3*,

Qingqing Ke1,2*

1School of Microelectronics Science and Technology, Sun Yat-sen university, Zhuhai

519082, China

2Guangdong Provincial Key Laboratory of Optoelectronic Information Processing

Chips and Systems, Sun Yat-sen University, Zhuhai 519082, China

3Joint Key Laboratory of the Ministry of Education, Institute of Applied Physics and

Materials Engineering, University of Macau, Taipa, Macau, China

* Corresponding authors

E-mail: yongqingcai@um.edu.mo; keqingq@mail.sysu.edu.cn

Abstract:

Recent discovery of a novel hexagonal phase of GeSe (γ-GeSe) has triggered great

interests in nanoelectronics applications owing to its electrical conductivity of bulk

phase even higher than graphite while its monolayer is a semiconductor. For potential

applications, construction of functional two-dimensional (2D) contacts is indispensable.

Herein, via first-principles calculations, we propose the design of van der Waals

heterostructures (vdWHs) of γ-GeSe contacting respectively with graphene, 2D h-BN

and MoS2, as representatives of metallic, insulator, and semiconductor partners. Our

work shows that the h-BN or graphene layer donates electrons to the γ-GeSe layer,

resulting in n doping in γ-GeSe, while the MoS2 layer accepts electrons from the γ-

GeSe layer leading to p doping of the latter. The γ-GeSe/BN heterostructure has a type-

I band alignment with large band offsets, indicating that BN can be used as an effective

passivating layer to protect γ-GeSe from its environmental disturbance while

maintaining its major electronic and optical characteristics. For γ-GeSe/graphene

heterostructure, it is prone to have a very low-Schottky barrier down to tens of meV,

easily overcome by thermal excitation, which can be tunable by strain and external

electric field. The γ-GeSe/MoS2 vdWH forms a Z-scheme interface, which is beneficial

for carriers splitting and photon utilization. Our work indicates that γ-GeSe can be well

passivated by BN, and form intimate contact with graphene for high charge injection

efficiency and with MoS2 for efficient carriers splitting for redox reactions.

Keywords: γ-GeSe, h-BN, graphene, MoS2, van der Waals heterostructures

1. Introduction

The successful exfoliation of graphene initiated a new era of two-dimensional (2D)

materials.1 A large family of 2D materials including transition metal dichalcogenides

(TMDs),2, 3 phosphorene,4, 5 hexagonal boron nitride (h-BN),6, 7 MXene,8, 9 have

attracted extensive attention owing to their distinct mechanical, electronic, and optical

properties. A single type of a 2D material generally cannot meet the requirements of

practical applications, and construction of van der Waals heterostructures (vdWHs)

with integrating different types of 2D layers together renders additional functionality

and promoted performance.10-15 The vdWHs also lead to exotic electronic properties

owing to the commensurate lattice or misfit stacking allowing manipulation of quasi-

particles dynamics within the vdW gap. In particular, interlayer excitons in vdWHs,

providing optically addressable spin and valley degrees of freedom and long lifetimes,

16 have become the hottest research area today. The exciton transistors,17 exciton

router,18 moiré excitons,19, 20 and the photo- and electro-luminescence from interlayer

excitons21, 22 have been achieved in vdWHs.

As one member of group IV monochalcogenide MX (M = Ge, Sn, Pb; X = S, Se, Te),

the layered α-GeSe has been extensively studied owing to its rich polymorphs,

phosphorene-like structure, excellent stability and environmental sustainability.23-26

Recently, a novel hexagonal phase of GeSe (γ-GeSe) with two merged blue-

phosphorus-like structure, has been synthesized for the first time.27 This new phase

shows striking features with a graphene-like semimetallic behavior, albeit highly

dependent on thickness, and its bulk phase shows a surprisingly better metallic

conductivity than graphite.27 Further, a strain-tunable spontaneous polarization and

spin-splitting in 2D form has been predicted through theoretical calculations.28

Consisting of solely s- and p-orbitals, the γ-GeSe shows the intriguing property of a

superior conduction in bulk form while a semiconducting nature in monolayer. This

renders it as an ideal platform as a passive layer, through forming heterostructures with

other 2D materials, for rectifying resistivity or contacts in 2D nanoelectronics. However,

how does such vdW hetero-interface consisting of γ-GeSe form, and its related

energetics and electronic properties such as lattice registration and band alignment are

still unknown albeit critically important.

In this work, we attempt to design the γ-GeSe based 2D heterostructures for various

functional contacts via first-principles calculations. We narrowed down its potential

partners to 2D graphene, BN, and MoS2 as representatives of metallic, insulator, and

semiconducting contacts, respectively. The vertically stacked γ-GeSe/BN, γ-

GeSe/graphene, and γ-GeSe/MoS2 vdWHs largely maintain the electronic structure of

GeSe due to its weak van der Waals force. The γ-GeSe/BN and γ-GeSe/MoS2 show a

Type-I and type-II band alignment (Z-scheme interface), respectively, while the γ-

GeSe/graphene possesses efficient thermally activated contact with a low Schottky

barrier of tens of meV. Our findings will be useful for the effective passivation of γ-

GeSe and functional integration for 2D nanoelectronics devices.

2. Computational methods

The first-principles calculations were carried out by the Vienna ab-initio simulation

package (VASP) with projector augmented wave (PAW) method.29, 30 The generalized

gradient approximation (GGA) with the Perdew−Burke−Ernzerhof (PBE) functional31

was employed to describe the exchange-correlation energy. A plane-wave basis set with

a cutoff of 400 eV was used for all calculations. The Brillouin zones were integrated

using the Gamma-centered k-points sampling with a reciprocal space resolution higher

than 2π × 0.02 Å-1 for geometry optimization and electronic structure calculations. The

convergence thresholds for residual force and total energy were 0.005 eV/Å and 10−8

eV, respectively. A vacuum layer over 20 Å in z-direction was set to avoid the periodic

interaction. The DFT-D3 corrections32, 33 was used for van der Waals interaction. The

Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional34 was also used to evaluate the

electronic structures. The thermal stability of the vdWHs was examined by the ab-initio

molecular dynamics (AIMD) simulations at 300 K for 10 ps with a time step of 2 fs.35

The interfacial binding energy (Eb) of the vdWHs was calculated by36

Eb = (EGeSe/X − EGeSe − EX)/S (1)

where EGeSe/X, EGeSe, and EX represent the total energy of the GeSe/X (X = h-BN,

graphene, 2H-MoS2) vdWH, the GeSe layer, and the X layer, respectively, and S

represents the surface area.

The differential charge density (DCD) Δρ(r) is defined as

Δρ = ρGeSe/X − ρGeSe − ρX (2)

where ρGeSe/X, ρGeSe, ρX are the charge densities of the GeSe/X vdWH, the GeSe layer,

and the X layer, respectively.

3. Results and Discussion

Geometric and electronic structure of the freestanding monolayers:

Before studying the GeSe/X vdWHs, the freestanding γ-GeSe and X monolayers were

first investigated. We calculated their band structures by the PBE (Fig.1) and HSE06

(Fig. S1) functionals, the results are summarized in Table 1. The lattice constants of γ-

GeSe, h-BN, graphene, and MoS2 are 3.76, 2.51, 2.47, and 3.15 Å, respectively,

文档加载中……请稍候！
如果长时间未打开，您也可以点击刷新试试。

下载文档到电脑，查找使用更方便

10 玖币 0人已下载

立即下载

摘要：

1VersatilevanderWaalsHeterostructuresofγ-GeSewithh-BN/Graphene/MoS2ChangmengHuan1,2,PuWang1,2,BingtaoLiu1,2,BinghanHe1,2,YongqingCai3*,QingqingKe1,2*1SchoolofMicroelectronicsScienceandTechnology,SunYat-senuniversity,Zhuhai519082,China2GuangdongProvincialKeyLaboratoryofOptoelectronicInformationProces...

展开>> 收起<<

1 Versatile van der Waals Heterostructures of γ-GeSe with h- BNGraphene MoS 2.pdf

共27页,预览5页

还剩页未读，继续阅读

声明：本站为文档C2C交易模式，即用户上传的文档直接被用户下载，本站只是中间服务平台，本站所有文档下载所得的收益归上传人(含作者)所有。玖贝云文库仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私，请立即通知玖贝云文库，我们立即给予删除！

1 Versatile van der Waals Heterostructures of γ-GeSe with h- BNGraphene MoS 2

相关推荐

开通VIP享超值会员特权

作者详情

相关内容

热门标签

举报选择: