High-Performance Humidity Sensors Based on Hexagonal Boron Nitride Films Prepared by Magnetron Sputtering

Humidity detection has attracted considerable attention from the scientific community. Hexagonal boron nitride (hBN) is an ideal material for humidity sensing due to its significant change in impedance with relative humidity (RH) and excellent chemical stability. In this work, we fabricated humidity sensors based on hBN films prepared by magnetron sputtering. The performance of the hBN humidity sensor was optimized by controlling the roughness and surface area of hBN films via the magnetron sputtering substrate temperature. The hBN films deposited at 600 °C showed outstanding sensitivity to relative humidity (>10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> Ohms/% RH), a high response value of 67.31 (defined as response=(Z<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub>-Z<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub>)/Z<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub>, Z<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> and Z<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> represent the impedance values under 11% and 95% RH, respectively), with the response and recovery time of 13.8 and 4.7 s. In continuous testing, the optimized hBN sensor exhibited high repeatability over a wide RH range with minimal humidity hysteresis (~3.53% RH) and excellent stability and reliability in a range of conditions, including high humidity, over time, and at high temperature. Moreover, the hBN sensor can detect the entire cyclic process of human exhalation and inhalation through current variations, making it effectively applicable in respiratory monitoring.