# Atomic-Scale Defects and Edge Engineering of ZrSe2 Nanosheets: Correlated Microscopy, Spectroscopy and DFT Study with Implications for Quantum Device Applications

## TL;DR

This study explores how atomic-scale defects and edge configurations affect the electronic properties of ZrSe2, offering insights for quantum device applications.

## Contribution

The paper provides atomic-level insights into defect and edge engineering in ZrSe2 for quantum devices.

## Key findings

- Intrinsic point defects in ZrSe2 introduce in-gap states and alter band edges.
- Grain boundaries preserve semiconducting character without deep in-gap states.
- Armchair edges show semiconducting behavior, while zigzag edges create midgap states.

## Abstract

We present a comprehensive study of the atomic-scale
electronic
behavior of ZrSe2, focusing on the effects of intrinsic
point defects, grain boundaries, and edge configurations. Using a
combination of low-temperature scanning tunnelling microscopy/spectroscopy
(STM/STS) and density functional theory (DFT), we identify and characterize
the spectroscopic fingerprints of various intrinsic point defects,
including vacancies, antisites, and interstitials, and reveal how
these features perturb the band edges or introduce in-gap states.
These defect-induced features are shown to significantly influence
the local electronic properties of ZrSe2. Our analysis
of grain boundaries identifies shear-type interfaces that shift the
Fermi level without introducing deep in-gap states, thereby preserving
the semiconducting character of pristine ZrSe2. In contrast,
the edge configuration has a pronounced effect on the electronic structure,
with armchair and zigzag edges exhibiting distinctly different behaviors.
While the former is characterized by a prominent peak near the valence
band edge, indicating the presence of edge-localized states and a
clean semiconducting character, the latter instead introduces a significant
density of states at midgap and within the upper half of the bandgap.
These findings offer atomic-level insights into the interplay between
defects, edge chemistry, and electronic behavior in ZrSe2, establishing a framework for defect- and edge-state engineering
in two-dimensional semiconductors for nanoelectronics and quantum
device applications.