Plasmonic Enhancement in Silver/Gallium-Doped Zinc Tin Oxide Thin-Film Transistor Photosensors: a Computational Investigation Using COMSOL Multiphysics

Altaei, Wisam M; Khorsheed, Suha M; Chazai, Alaa J

doi:10.22075/ppam.2026.41308.1232

Plasmonic Enhancement in Silver/Gallium-Doped Zinc Tin Oxide Thin-Film Transistor Photosensors: a Computational Investigation Using COMSOL Multiphysics

Document Type : Original Article

Authors

Wisam M Altaei ¹

Suha M Khorsheed ¹

Alaa J Chazai ²

¹ Department of Physics, College of Science, Al-Nahrain University, Baghdad, Iraq

² Department of Medical Physics, College of Science, Al-Nahrain University, Baghdad, Iraq

10.22075/ppam.2026.41308.1232

Abstract

Photosensors have become important building blocks in modern optoelectronics, yet their performance often hits a ceiling when conventional designs are employed. This work explores how plasmonic effects can push these boundaries further. We present a detailed computational study of silver/gallium-doped zinc tin oxide thin-film transistor photosensors using finite element analysis in COMSOL Multiphysics. A three-dimensional model measuring 420 nm × 300 nm × 135 nm was developed, featuring a bottom-gate design with a 20 nm silver electrode, a 60 nm silicon dioxide insulator, and a dual-layer semiconductor channel. Simulation results demonstrate remarkable field enhancement exceeding 12× at the plasmon resonance wavelength of 380 nm, with a penetration depth of approximately 50 nm. The transfer characteristics indicate a threshold voltage of −0.8 V, a field-effect mobility of 18.5 cm²/V·s, and a subthreshold swing of 285 mV/decade. Broadband photoresponsivity enhancement is observed across the UV–visible spectrum (350–550 nm).

Keywords

Plasmonics

Oxide semiconductors

Photosensor

COMSOL Multiphysics

Drude model

Thin-film transistor

Subjects

Plasmonic

© 2026 The Author(s). Progress in Physics of Applied Materials published by Semnan University Press. This is an open access article under the CC-BY 4.0 license. (https://creativecommons.org/licenses/by/4.0/)

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