Abstract
We investigate the effects of postdeposition annealing (PDA) ambience on the nitrogen dioxide (NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) gas sensing performance in the Si-based field-effect transistor (FET)-type gas sensor having an indium–gallium–zinc oxide (IGZO) as a sensing material. After the IGZO thin films are deposited, the sensors are postannealed in vacuum and atmospheric ambiences. The content of oxygen vacancy in IGZO films varies depending on the PDA ambience, which changes the electrical properties and NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas sensing performance of the sensors. The sensor postannealed in a vacuum ambience has more oxygen vacancy, which acts as an electrical donor, than that in an atmospheric ambience. Thus, the former has a larger coupling ratio and transconductance of the FET transducer. Also, the oxygen vacancy produces negatively charged oxygen species, increasing the response to NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Due to a larger response to NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gas and low noise, the sensor postannealed in a vacuum shows excellent signal-to-noise ratio (SNR) and limit-of-detection performances.
Published Version
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