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Open AccessFeature PaperArticle

Ta2O5/SiO2 Multicomponent Dielectrics for Amorphous Oxide TFTs

i3N/CENIMAT, Department of Materials Science, NOVA School of Science and Technology and CEMOP/UNINOVA, NOVA University Lisbon, Campus de Caparica, 2829-516 Caparica, Portugal
IPFN, Instituto Superior Técnico, University of Lisbon, EN 10, km 139,7 2695-066 Bobadela, Portugal
Authors to whom correspondence should be addressed.
Electron. Mater. 2021, 2(1), 1-16;
Received: 11 November 2020 / Revised: 10 December 2020 / Accepted: 22 December 2020 / Published: 29 December 2020
(This article belongs to the Special Issue Feature Papers of Electronic Materials)
Co-sputtering of SiO2 and high-κ Ta2O5 was used to make multicomponent gate dielectric stacks for In-Ga-Zn-O thin-film transistors (IGZO TFTs) under an overall low thermal budget (T = 150 °C). Characterization of the multicomponent layers and of the TFTs working characteristics (employing them) was performed in terms of static performance, reliability, and stability to understand the role of the incorporation of the high-κ material in the gate dielectric stack. It is shown that inherent disadvantages of the high-κ material, such as poorer interface properties and poor gate insulation, can be counterbalanced by inclusion of SiO2 both mixed with Ta2O5 and as thin interfacial layers. A stack comprising a (Ta2O5)x(SiO2)100 − x film with x = 69 and a thin SiO2 film at the interface with IGZO resulted in the best performing TFTs, with field-effect mobility (µFE) ≈ 16 cm2·V−1·s−1, subthreshold slope (SS) ≈ 0.15 V/dec and on/off ratio exceeding 107. Anomalous Vth shifts were observed during positive gate bias stress (PGBS), followed by very slow recoveries (time constant exceeding 8 × 105 s), and analysis of the stress and recovery processes for the different gate dielectric stacks showed that the relevant mechanism is not dominated by the interfaces but seems to be related to the migration of charged species in the dielectric. The incorporation of additional SiO2 layers into the gate dielectric stack is shown to effectively counterbalance this anomalous shift. This multilayered gate dielectric stack approach is in line with both the large area and the flexible electronics needs, yielding reliable devices with performance suitable for successful integration on new electronic applications. View Full-Text
Keywords: Ta2O5/SiO2; TFTs; anomalous Vth shift; multicomponent dielectrics; high-κ dielectrics Ta2O5/SiO2; TFTs; anomalous Vth shift; multicomponent dielectrics; high-κ dielectrics
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MDPI and ACS Style

Martins, J.; Kiazadeh, A.; Pinto, J.V.; Rovisco, A.; Gonçalves, T.; Deuermeier, J.; Alves, E.; Martins, R.; Fortunato, E.; Barquinha, P. Ta2O5/SiO2 Multicomponent Dielectrics for Amorphous Oxide TFTs. Electron. Mater. 2021, 2, 1-16.

AMA Style

Martins J, Kiazadeh A, Pinto JV, Rovisco A, Gonçalves T, Deuermeier J, Alves E, Martins R, Fortunato E, Barquinha P. Ta2O5/SiO2 Multicomponent Dielectrics for Amorphous Oxide TFTs. Electronic Materials. 2021; 2(1):1-16.

Chicago/Turabian Style

Martins, Jorge; Kiazadeh, Asal; Pinto, Joana V.; Rovisco, Ana; Gonçalves, Tiago; Deuermeier, Jonas; Alves, Eduardo; Martins, Rodrigo; Fortunato, Elvira; Barquinha, Pedro. 2021. "Ta2O5/SiO2 Multicomponent Dielectrics for Amorphous Oxide TFTs" Electron. Mater. 2, no. 1: 1-16.

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