Anisotropic Dopant and Strain Architectures in WS$_2$ Nanocrystals Driven by Growth Kinetics

TL;DR

This study demonstrates how non-equilibrium growth kinetics can be used to create deterministic dopant and strain architectures in WS$_2$ monolayers, enabling programmable defect landscapes during synthesis.

Contribution

It introduces a kinetic model for dopant segregation and shows how anisotropic dopant distribution induces localized strain in 2D WS$_2$.

Findings

Preferential vanadium incorporation along crystallographic bisectors.

Localized tensile strain channels associated with dopant distribution.

Emergence of a localized $J2$ vibrational mode linked to V-V oscillations.

Abstract

Dopant distribution in two-dimensional semiconductors is typically assumed to be stochastic, limiting deterministic defect engineering. Here, we show that non-equilibrium growth kinetics can be harnessed to define dopant-driven strain architectures in vanadium-doped WS$_2$ monolayers. Using synchrotron X-ray fluorescence, we identify preferential vanadium incorporation, anti-correlated with tungsten content, along crystallographic bisectors. An adsorption-growth-diffusion model with a single kinetic parameter quantitatively captures the dopant segregation arising from preferential corner adsorption and limited diffusion during chemical vapor deposition growth. Hyperspectral Raman imaging demonstrates mechanically induced vibrational responses, revealing localized tensile strain ($\varepsilon \approx0.70\%$) channels associated with the anisotropic dopant distribution. This regime is marked by the depletion of W-site-sensitive in-plane modes and the emergence of a localized $J2$ mode (210~cm$^{-1}$), which our ab-initio calculations attribute to antiphase V$-$V oscillations. These findings establish kinetic segregation as a route to deterministic chemical and strain architectures in 2D semiconductors, enabling programmable defect landscapes and strain engineering during synthesis.