Atomic scale depletion region at one dimensional MoSe2-WSe2 heterointerface

Abstract

Lateral heterojunctions based on two dimensional (2D) transition metal dichalcogenides (TMDCs) potentially realize monolayer devices exploiting 2D electronic structures and the functions introduced by the presence of 1D heterointerfaces. Electronic structures of a lateral MoSe2-WSe2 junction have been unveiled using scanning tunneling microscopy and spectroscopy. A smooth and narrow depletion region exists despite a defect-rich heterointerface deviating from the preferred zigzag orientations of the TMDC lattice. From the characteristics of the depletion region, a high carrier concentration and high internal electric fields are inferred, offering to benefit designs of lateral TMDC devices.

Local Electronic Properties of Coherent Single-Layer WS2/WSe2 Lateral Heterostructures

“…8−11 Irregular MoSe 2 /WSe 2 interfaces have been observed to exhibit type-II band alignments and narrow transition regions, but this system does not allow intrinsic strain engineering due to the nearly identical lattice constants of TMDs with the same chalcogen atoms (i.e., Se in MoSe 2 and WSe 2 ). 12 HSs of WSe 2 /MoS 2 , on the other hand, have a lattice mismatch of approximately 4% (sulfides smaller than selenides) which has resulted in strong spatial variation in the electronic structure of MoS 2 caused by the irregular interface strain field. 7 Recently Li et al 3 and Xie et al 10 have shown that it is possible to fabricate lateral heterojunctions between different TMD materials that are defect-free despite large lattice mismatches.…”

“…Semiconductor heterostructures (HSs) are composed of two different semiconducting materials that make contact at a junction interface. While most heterojunctions in van der Waals materials occur in the vertical (out-of-plane) direction, a number of atomically flat lateral heterojunctions have also been characterized. − For example, WS 2 /WSe 2 and MoSe 2 /WSe 2 heterojunctions made using chemical vapor deposition (CVD) techniques have been observed to exhibit diode-like responses and photovoltaic effects. ,, Lattice-mismatched in-plane HSs have also been shown to provide a platform for altering TMD electronic structure by means of strain engineering. − Irregular MoSe 2 /WSe 2 interfaces have been observed to exhibit type-II band alignments and narrow transition regions, but this system does not allow intrinsic strain engineering due to the nearly identical lattice constants of TMDs with the same chalcogen atoms (i.e., Se in MoSe 2 and WSe 2 ) . HSs of WSe 2 /MoS 2 , on the other hand, have a lattice mismatch of approximately 4% (sulfides smaller than selenides) which has resulted in strong spatial variation in the electronic structure of MoS 2 caused by the irregular interface strain field .…”

The search for manganese incorporation in MoSe 2 monolayer epitaxially grown on graphene

“…From our own experience and from published works, we know that variable bias imaging allows for the detection of isoelectronic substitutional atoms in TMD layers, such as O on S/Se sites [27] or Mo on W sites [28,29]. We expect that the incorporation of non-isoelectronic dopants such as Mn in MoSe 2 , would give rise to a larger perturbation in the local electronic structure of the TMD matrix, and thus to a contrast (on the nanometer size) that should be easily observed using STM, as recently achieved in WSe 2 flakes doped with V atoms [26].…”

Plasma Treatment of Ultrathin Layered Semiconductors for Electronic Device Applications

“…Knowing that the material systems in question here are susceptible to crystal structure modification due to plasma treatmentby both etching and chemical substitutionwe can contextualize what this means for charge transport in these low-dimensional systems. The ability to freely and controllably introduce defects and dopants into 2D semiconductors allows one to potentially tune the various well-understood parameters at the heart of FET device physics, namely, the gate threshold voltage, , charge carrier mobility, , trap density, , contact resistance, ,, Fermi level pinning, , the nature of the depletion region, , subthreshold swing, ,, hot carrier injection, − noise in the drive current, − free carrier screening ,,, and the dielectric environment at large. , Although an exhaustive list would include many more parameters here, we go on to overview the effects of plasma treatment on some of these electrical characteristics in FETs based on 2D semiconductors.…”