Photovoltaic self-powered gas sensors are generally based on the device structure of a p-n photodiode, which requires two different electrodes on opposite sides of a heterojunction. However, the complicated structure...
The fabrication of a conventional photodetector array (PDA) involves complex photolithography technology for pixel isolation. An easy process is essential for the mass production of PDAs. This study explores a facile method of fabricating a PDA that comprises 4 × 4 p-Cu 2 O/n-Si photodiode cells. A solutionprocessed p-type Cu 2 O film is patterned by removing the UVshielded portion by immersing it in water. The efficient separation of electron/hole pairs at the Cu 2 O/Si interface enables selfpowered operation with a responsivity of 0.3 A/W and a fast response speed (∼10 ms). The PDA has relatively good uniformity and negligible variation between pixels. It records simple characters with a satisfactory resolution and exhibits negligible degradation over 3 months. The combination of self-powering characteristics, high reliability, and easy processability indicates that this PDA can be used for image sensing applications.
Traditional gas sensors require an external voltage to provide a readout signal for measuring the resistance/current changes. To reduce the power consumption and working area for system-on-chip applications, photovoltaic self-powered gas sensors are a promising strategy. However, most of the reported self-powered gas sensors are based on a vertical p−n junction structure with two different electrodes located on opposite sides, which is incompatible with planar circuit technology. In this study, a metal−semiconductor−metal (MSM) selfpowered ozone (O 3 ) gas sensor based on a-IGZO is successfully fabricated using localized ultraviolet treatment (UVT) which is used to selectively modify the surface states underneath different contacts. The established asymmetric Schottky barrier results in self-powered characteristics under UV illumination. The self-powered gas sensor exhibits an unbiased gas response of 74% with a response/ recovery time of 168/522 s toward 5 ppm of O 3 at room temperature. The proposed method provides insights for easy fabrication of photovoltaic self-powered gas sensors using a highly integrated MSM structure.
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