Transparent Conductive Oxides-based Architectures for the Electrical Modulation of the Optical Response: A Spectroscopic Ellipsometry Study

TL;DR

This study uses spectroscopic ellipsometry to explore how electrical gating influences the optical properties of aluminum-doped ZnO thin films, aiming to enable combined electrical and optical control in optoelectronic devices.

Contribution

It demonstrates the in-operando measurement of dielectric property variations in AZO films under electrical bias, advancing understanding of tunable transparent conductive oxides.

Findings

Electrical bias affects AZO dielectric properties.

Charge injection/depletion modulates optical response.

Potential for integrated electrical and optical device control.

Abstract

Transparent Conductive Oxides (TCOs) are a class of materials that combine high optical transparency with high electrical conductivity. This property makes them uniquely appealing as transparent-conductive electrodes in solar cells and interesting for optoelectronics and infrared-plasmonics applications. One of the new challenges that researchers and engineers are facing is merging optical and electrical control in a single device for developing next-generation photovoltaic, opto-electronic devices and energyefficient solid-state lighting. In this work, we investigated the possible variations in the dielectric properties of aluminum-doped ZnO (AZO) upon gating, by means of Spectroscopic Ellipsometry (SE). We investigated the electrical-bias-dependent optical response of thin AZO films fabricated by magnetron sputtering, within a parallel-plane capacitor configuration. We address the possibility to control their optical and electric performances by applying bias, monitoring the effect of charge injection/depletion in the AZO layer by means of in-operando SE vs applied gate voltage.