Electrically activated W-doped VO2 films for reliable, large-area, broadband THz waves modulators

TL;DR

This paper presents W-doped VO2 films as reliable, large-area, broadband THz modulators with electrically controllable phase transitions, advancing the development of practical THz communication devices.

Contribution

It demonstrates that W doping enables tuning and control of the insulator-metal transition in VO2, improving THz modulation capabilities.

Findings

W doping shifts the IMT temperature of VO2.

W doping controls the spatial distribution of the IMT.

The devices exhibit reliable, broadband THz modulation.

Abstract

THz amplitude modulators and switches are considered to be the main building blocks of future THz communication systems. Despite rapid progress, modulation and switching devices in this electromagnetic spectrum lag far behind other frequency ranges. Currently, THz modu-lators face major challenges in consistently producing high modulations depths over large frequency bands. Moreover, a convenient integration for practical applications requires that the modulation/switching properties can be electrically controlled. Devices fulfilling all these con-ditions remain to be demonstrated. In this work we show that W-doped VO2 films grown by direct-current magnetron sputtering can be efficiently used for the development reliable, large-area, broadband THz waves modulators. We demonstrate that W doping not only permits to tune the insulator to metal transition (IMT) temperature of VO2, but also, most importantly, to control the topology of the electrically activated transition. In situ / operando X-ray diffraction and Raman spectroscopy characterizations of the devices, coupled with standard resistivi-ty measurements and time-domain THz spectroscopy, unambiguously demonstrate that the changes in the spatial distribution of the IMT is due to structural distortions induced by W doping.