High-mobility and low subthreshold swing amorphous InGaZnO thin-film transistors by in situ H2plasma and neutral oxygen beam irradiation treatment

Chien-Hung Wu; Srikant Kumar Mohanty; Bo-Wen Huang; Kow-Ming Chang; Shui-Jinn Wang; Kung-Jeng Ma

doi:10.1088/1361-6528/acb5f9

High-mobility and low subthreshold swing amorphous InGaZnO thin-film transistors by in situ H₂plasma and neutral oxygen beam irradiation treatment

Nanotechnology. 2023 Feb 10;34(17). doi: 10.1088/1361-6528/acb5f9.

Authors

Chien-Hung Wu¹, Srikant Kumar Mohanty², Bo-Wen Huang³, Kow-Ming Chang³, Shui-Jinn Wang⁴, Kung-Jeng Ma¹

Affiliations

¹ Department of Optoelectronics & Materials Engineering, Chung Hua University, Hsinchu, 30010, Taiwan, ROC.
² UST-IPPP, College of Electrical and Computer Engineering, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC.
³ Institute of Electronics, National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan, ROC.
⁴ Department of Electrical Engineering, National Cheng Kung University, Tainan, Taiwan, ROC.

PMID: 36696686
DOI: 10.1088/1361-6528/acb5f9

Abstract

In this work, staggered bottom-gate structure amorphous In-Ga-Zn-O (a-IGZO) thin film transistors (TFTs) with high-k ZrO₂gate dielectric were fabricated using low-cost atmospheric pressure-plasma enhanced chemical vapor deposition (AP-PECVD) within situhydrogenation to modulate the carrier concentration and improve interface quality. Subsequently, a neutral oxygen beam irradiation (NOBI) technique is applied, demonstrating that a suitable NOBI treatment could successfully enhance electrical characteristics by reducing native defect states and minimize the trap density in the back channel. A reverse retrograde channel (RRGC) with ultra-high/low carrier concentration is also formed to prevent undesired off-state leakage current and achieve a very low subthreshold swing. The resulting a-IGZO TFTs exhibit excellent electrical characteristics, including a low subthreshold swing of 72 mV dec^-1and high field-effect mobility of 35 cm²V^-1s^-1, due to conduction path passivation and stronger carrier confinement in the RRGC. The UV-vis spectroscopy shows optical transmittance above 90% in the visible range of the electromagnetic spectrum. The study confirms the H₂plasma with NOBI-treated a-IGZO/ZrO₂TFT is a promising candidate for transparent electronic device applications.

Keywords: InGaZnO; amorphous; mobility; subthreshold; swing; thin-film transistors.