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A Sustainable Approach to Flexible Electronics with Zinc‐Tin Oxide Thin‐Film Transistors
Author(s) -
Fernandes Cristina,
Santa Ana,
Santos Ângelo,
Bahubalindruni Pydi,
Deuermeier Jonas,
Martins Rodrigo,
Fortunato Elvira,
Barquinha Pedro
Publication year - 2018
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.201800032
Subject(s) - materials science , thin film transistor , optoelectronics , amorphous solid , transistor , subthreshold slope , semiconductor , threshold voltage , gate dielectric , nanotechnology , electrical engineering , voltage , layer (electronics) , chemistry , organic chemistry , engineering
Zinc‐tin oxide (ZTO) is widely invoked as a promising indium and gallium‐free alternative for amorphous oxide semiconductor based thin‐film transistors (TFTs). The main bottleneck of this semiconductor material compared to mainstream indium‐gallium‐zinc oxide (IGZO) is centered in the larger processing temperatures required to achieve acceptable performance (>300 °C), not compatible with low‐cost flexible substrates. This work reports for the first time flexible amorphous‐ZTO TFTs processed at a maximum temperature of 180 °C. Different aspects are explored to obtain performance levels comparable to IGZO devices at these low processing temperatures, such as hydrogen incorporation during ZTO sputtering and integration with a high‐κ multilayer/multicomponent dielectric. Close‐to‐zero turn‐on voltage, field‐effect mobility ≈5 cm 2 V −1 s −1 , and subthreshold slope of 0.26 V dec −1 are obtained. Stability under negative‐bias‐illumination stress is dramatically improved with hydrogen incorporation in ZTO and device performance is insensitive to bending under a radius of curvature of 15 mm. Inverters using the ZTO TFTs enable rail‐to‐rail operation with supply voltage V DD as low as 5 V, while a differential amplifier with positive feedback loop provides a gain of 17 dB and unity gain frequency of 40 kHz, limited by the large gate‐to‐source and gate‐to‐drain overlaps used herein.