Optical response of WSe$_2$-based vertical tunneling junction

TL;DR

This study explores the optical properties of a WSe₂-based vertical tunneling junction, revealing how bias voltage influences carrier concentration and excitonic emissions through photoluminescence and electroluminescence measurements at low temperature.

Contribution

It provides new insights into the bias-dependent optical response and excitonic behavior of WSe₂ heterostructures under low-temperature conditions.

Findings

Bias voltage alters carrier sign and concentration.

Multiple excitonic complexes observed in PL spectra.

Distinct excitation mechanisms for PL and EL emissions.

Abstract

Layered materials have attracted significant interest because of their unique properties. Van der Waals heterostructures based on transition-metal dichalcogenides have been extensively studied because of potential optoelectronic applications. We investigate the optical response of a light-emitting tunneling structure based on a WSe\textsubscript{2} monolayer as an active emission material using the photoluminescence (PL) and electroluminescence (EL) experiments performed at low temperature of 5~K. We found that the application of the bias voltage allows us to change both a sign and a value of free carriers concentrations. Consequently, we address the several excitonic complexes emerging in PL spectra under applied bias voltage. The EL signal was also detected and ascribed to the emission in a high-carrier-concentration regime. The results show that the excitation mechanisms in the PL and EL are different, resulting in various emissions in both types of experimental techniques.