Anisotropic Carrier Mobility from 2H WSe2

Anisotropic Carrier Mobility from 2H WSe2

by | Jan 1, 2022 | 2022, 本组论文

Advanced Materials 34, 2108615 (2022)

Ping Chen, Jinbo Pan, Wenchao Gao, Bensong Wan, Xianghua Kong, Yang Cheng, Kaihui Liu, Shixuan Du, Wei Ji, Caofeng Pan & Zhong Lin Wang

Abstract

Transition metal dichalcogenides (TMDCs) with 2H phase are expected to be building blocks in next-generation electronics; however, they suffer from electrical anisotropy, which is the basics for multi-terminal artificial synaptic devices, digital inverters, and anisotropic memtransistors, which are highly desired in neuromorphic computing. Herein, the anisotropic carrier mobility from 2H WSe2 is reported, where the anisotropic degree of carrier mobility spans from 0.16 to 0.95 for various WSe2 field-effect transistors under a gate voltage of −60 V. Phonon scattering, impurity ions scattering, and defect scattering are excluded for anisotropic mobility. An intrinsic screening layer is proposed and confirmed by Z-contrast scanning transmission electron microscopy (STEM) imaging to respond to the electrical anisotropy. Seven types of intrinsic screening layers are created and calculated by density functional theory to evaluate the modulated electronic structures, effective masses, and scattering intensities, resulting in anisotropic mobility. The discovery of anisotropic carrier mobility from 2H WSe2 provides a degree of freedom for adjusting the physical properties of 2H TMDCs and fertile ground for exploring and integrating TMDC electronic transistors with better performance along the direction of high mobility.

Band alignment and interlayer hybridization in monolayer organic/WSe2 heterojunction

Band alignment and interlayer hybridization in monolayer organic/WSe2 heterojunction

by | Jan 1, 2022 | 2022, 本组论文

Nano Research 15, 1276–1281 (2022)

Yanping Guo, Linlu Wu, Jinghao Deng, Linwei Zhou, Wei Jiang, Shuangzan Lu, Da Huo, Jiamin Ji, Yusong Bai, Xiaoyu Lin, Shunping Zhang, Hongxing Xu, Wei Ji & Chendong Zhang

Abstract

Semiconducting heterojunctions (HJs), comprised of atomically thin transition metal dichalcogenides (TMDs), have shown great potentials in electronic and optoelectronic applications. Organic/TMD hybrid bilayers hold enhanced pumping efficiency of interfacial excitons, tunable electronic structures and optical properties, and other superior advantages to these inorganic HJs. Here, we report a direct probe of the interfacial electronic structures of a crystalline monolayer (ML) perylene-3,4,9,10-tetracarboxylic-dianhydride (PTCDA)/ML-WSe2 HJ using scanning tunneling microscopy, photoluminescence, and first-principle calculations. Strong PTCDA/WSe2 interfacial interactions lead to appreciable hybridization of the WSe2 conduction band with PTCDA unoccupied states, accompanying with a significant amount of PTCDA-to-WSe2 charge transfer (by 0.06 e/PTCDA). A type-II band alignment was directly determined with a valence band offset of ∼ 1.69 eV, and an apparent conduction band offset of ∼ 1.57 eV. Moreover, we found that the local stacking geometry at the HJ interface differentiates the hybridized interfacial states.