Oxide semiconductor gas sensors are widely used for detecting toxic, explosive, and flammable gases due to their simple structure, cost-effectiveness, and potential integration into compact devices. However, their reliable gas detection is hindered by a longstanding issue known as humidity dependence, wherein the sensor resistance and gas response change significantly in the presence of moisture. This problem has persisted since the inception of oxide semiconductor gas sensors in the 1960s. This paper explores the root causes of humidity dependence in oxide semiconductor gas sensors and presents strategies to address this challenge. Mitigation strategies include functionalizing the gas-sensing material with noble metal/transition metal oxides and rare-earth/rare-earth oxides, as well as implementing a moisture barrier layer to prevent moisture diffusion into the gas-sensing film. Developing oxide semiconductor gas sensors immune to humidity dependence is expected to yield substantial socioeconomic benefits by enabling medical diagnosis, food quality assessment, environmental monitoring, and sensor network establishment.

Citations

• Colorimetric Gas Sensors Based on Metal Oxide and Metal Halide Nanostructures for Rapid Detection of Hydrogen and Ammonia Leakage in Eco-Friendly Marine Vessels
  Haemyeong In, Changyun Kim, Kwonho Jang, Chae Young Woo, Hyung Woo Lee, Ji Wook Yoon, Myungkwan Song, Kang Hyun Park
  Applied Science and Convergence Technology.2026; 35(5): 151.     CrossRef

We have investigated the characteristics of amorphous silicon (a-Si) thin-film solar cell by inserting barrier layer. The conversion efficiency of a-Si thin-film solar cells on graphite substrate shows nearly zero because of the surface roughness of the graphite substrate. To enhance the performance of solar cells, the surface morphology of the back side were modified by changing the barrier layer on graphite. The surface roughness of graphite substrate with the barrier layer grown by plasma enhanced chemical vapor deposition (PECVD) reduced from ~2 um to ~75 nm. In this study, the combination of the barrier layer on graphite substrate is important to increase solar cell efficiency. We achieved ~ 7.8% cell efficiency for an a-Si thin-film solar cell on graphite substrate with SiNx/SiOx stack barrier layer.

Citations

• Feasibility Study of the Introduction of Hydrogen System and Plus DR on Campus MG
  Gyuha Woo, Soojin Park, Yongbeum Yoon
  New & Renewable Energy.2022; 18(1): 35.     CrossRef