Scanning tunneling microscopy investigations of transition metal dichalcogenide 1t-tantalum disulfide and zigzag-shape graphene nanoribbons in ultra-high vacuum

This thesis demonstrates the studies of 1T-TaS2, a member of the transition metal dichalcogenides (TMDCs) family, and wet-chemically synthesized zigzag-shape graphene nanoribbons (GNRs) on hydrogen passivated silicon substrate through scanning tunneling microscopy (STM). Dry contact transfer allows unperturbed transfer and exfoliation of desired two-dimensional (2D) layered materials onto a desired substrate under ultra-high vacuum (UHV), to largely prevent potential solvent and atmospheric contamination. STM imaging and scanning tunneling spectroscopy (STS) measurements provide preliminary results on lattice structure of possibly monolayer or few- layer 1T-TaS2 under room temperature. Exploration of existence of charge density waves (CDWs) in monolayer 1T-TaS2 is in progress. Past work on surface modification of another TMDC material, MoS2, using STM has shown successful removal of desired atoms to form letters on the sample surface. Hypothesis of modifying monolayer 1T-TaS2 surface structure using similar technique may result in intriguing mechanical or electronic properties. Detailed STM imaging and STS measurements of wet chemically synthesized zigzag shape GNRs exhibit an atomic structure matching the expected molecular formula, and alternating bandgap energies of 0.4 eV and 2.68 eV, presumably due to the alternating armchair and zigzag edge terminations.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Electrical & Computer Engr

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2022

Author dc:creator

• Wang, Hanfei

Contributors dc:contributor

• Lyding, Joseph

• Scanning tunneling microscopy
• 2D materials

Statement dc:rights

• Copyright 2021 Hanfei Wang

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/113342

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/113342