Study of humidity sensor using α‐Fe₂O₃ as a humidity‐sensitive material

Abstract

In this study, iron oxide thin films are prepared under various heat treatment conditions, and their crystal structures and moisture‐sensitive characteristics were evaluated to clarify the usefulness of iron oxide thin films as humidity‐sensitive materials for humidity sensors. In addition, the possibility of a humidity sensor with a wide dynamic range was investigated by evaluating the relationship between the film thickness of the iron oxide thin film, the electrode width of the device, and the humidity‐sensitive characteristics. As a result, it was found that the crystal structure of α‐Fe2O3 exhibits relatively good humidity sensitivity compared to other crystal structures, and that the sensitivity to humidity can be adjusted by appropriately selecting the electrode width and film thickness of the device. Therefore, the α‐Fe2O3 thin film may be useful as a moisture‐sensitive material for wide dynamic range humidity sensors by appropriately adjusting the film thickness and electrode width.