Semiconductor-to-Metal Transition in the Bulk of WSe2 upon Potassium Intercalation

TL;DR

This study demonstrates that potassium intercalation induces a semiconductor-to-metal transition in bulk WSe2, evidenced by plasmon excitation and dielectric function analysis, revealing a specific doped phase with notable plasmon dispersion.

Contribution

First detailed spectroscopic analysis showing the electronic transition and phase formation in K-intercalated WSe2.

Findings

Charge carrier plasmon at 0.97 eV indicates metallic behavior.

Formation of a K0.6WSe2 phase confirmed.

Significant plasmon dispersion observed.

Abstract

We present electron energy-loss spectroscopic measurements of potassium (K) intercalated tungsten diselenide (WSe2). After exposure of pristine WSe2 films to potassium, we observe a charge carrier plasmon excitation at about 0.97 eV, which indicates a semiconductor to metal transition. Our data signal the formation of one particular doped K-WSe2 phase. A Kramers-Kronig analysis (KKA) allows the determination of the dielectric function and to estimate the composition of about K0.6WSe2. Momentum dependent measurements reveal a substantial plasmon dispersion to higher energies.