Optimization of Aluminum Dopant Amalgamation Immersion Time on Structural, Electrical, and Humidity-Sensing Attributes of Pristine ZnO for Flexible Humidity Sensor Application
A Shamsul Rahimi A Subki,
Mohamad Hafiz Mamat,
Musa Mohamed Zahidi,
Mohd Hanapiah Abdullah,
I. B. Shameem Banu,
Nagamalai Vasimalai,
Mohd Khairul Ahmad,
Nafarizal Nayan,
Suriani Abu Bakar,
Azmi Mohamed,
Muhammad Danang Birowosuto,
Mohamad Rusop Mahmood
Affiliations
A Shamsul Rahimi A Subki
NANO-ElecTronic Centre (NET), School of Electrical Engineering, College of Engineering, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
Mohamad Hafiz Mamat
NANO-ElecTronic Centre (NET), School of Electrical Engineering, College of Engineering, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
Musa Mohamed Zahidi
NANO-ElecTronic Centre (NET), School of Electrical Engineering, College of Engineering, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
Mohd Hanapiah Abdullah
NANO-ElecTronic Centre (NET), School of Electrical Engineering, College of Engineering, Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
I. B. Shameem Banu
School of Physical and Chemical Sciences, B. S. Abdur Rahman Crescent Institute of Science & Technology, Chennai 600 048, Vandalur, India
Nagamalai Vasimalai
School of Physical and Chemical Sciences, B. S. Abdur Rahman Crescent Institute of Science & Technology, Chennai 600 048, Vandalur, India
Mohd Khairul Ahmad
Microelectronic and Nanotechnology—Shamsuddin Research Centre, Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat 86400, Johor, Malaysia
Nafarizal Nayan
Microelectronic and Nanotechnology—Shamsuddin Research Centre, Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, Batu Pahat 86400, Johor, Malaysia
Suriani Abu Bakar
Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim 35900, Perak, Malaysia
Azmi Mohamed
Nanotechnology Research Centre, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Tanjung Malim 35900, Perak, Malaysia
Muhammad Danang Birowosuto
Lukasiewicz Research Network—PORT Polish Center for Technology Development, Stabłowicka 147, 54-066 Wroclaw, Poland
Mohamad Rusop Mahmood
NANO-SciTech Lab, Centre for Functional Materials and Nanotechnology, Institute of Science (IOS), Universiti Teknologi MARA, Shah Alam 40450, Selangor, Malaysia
This study synthesized pristine and aluminum (Al)-doped zinc oxide (Al:ZnO) nanostructures through a simplistic low-temperature ultrasonicated solution immersion method. Al:ZnO nanostructures were synthesized as a sensing material using different immersion times varying from two to five hours. The Al:ZnO nanostructured-based flexible humidity sensor was fabricated by employing cellulose filter paper as a substrate and transparent paper glue as a binder through a simplistic brush printing technique. XRD, FESEM, HRTEM, EDS, XPS, a two-probe I–V measurement system, and a humidity measurement system were employed to investigate the structural, morphological, chemical, electrical, and humidity-sensing properties of the pristine ZnO and Al:ZnO nanostructures. The structural and morphological analysis confirmed that Al cations successfully occupied the Zn lattice or integrated into interstitial sites of the ZnO lattice matrix. Humidity-sensing performance analysis indicated that the resistance of the Al:ZnO nanostructure samples decreased almost linearly as the humidity level increased, leading to better sensitivity and sensing response. The Al:ZnO-4 h nanostructured-based flexible humidity sensor had a maximum sensing response and demonstrated the highest sensitivity towards humidity changes, which was noticeably superior to the other tested samples. Finally, this study explained the Al:ZnO nanostructures-based flexible humidity sensor sensing mechanism in terms of chemical adsorption, physical adsorption, and capillary condensation mechanisms.
