講演情報
[9p-A11-9]WS2-based SAW Gas Sensor: Intrinsic NH3 Selectivity and UV-induced Ethanol Selectivity
〇Zhexuan Zhao1, Sankar Ganesh Ramaraj1, Chen Li2, TABATA Hitoshi1, YAMAHARA Hiroyasu1, Kiriya Daisuke2 (1.UTokyo Eng., 2.UTokyo GSAS)
キーワード：
gas sensor、2D material
Volatile gases from human breath and skin provide useful information for non-invasive biomarker monitoring. In this study, a WS2-based SAW gas sensor was investigated to improve gas selectivity by UV surface treatment. Gas adsorption on the WS2 sensing layer changes SAW propagation through mass loading, elastic perturbation, and acoustoelectric effects. Pristine WS2 shows intrinsic NH3 selectivity, mainly due to the interaction between Lewis-basic NH3 molecules and Lewis-acidic SO4^2--related surface sites, together with electron donation from NH3 to p-type WS2. Raman analysis confirmed exfoliated WS2 on the SiO2/LiTaO3 substrate, with a strong peak near 350 cm^-1 assigned to overlapping 2LA(M) and E2g^1 modes and a weaker A1g mode near 420 cm^-1. After UV treatment, the ethanol response was significantly enhanced. The UV-treated WS2-SAW sensor showed a clear frequency shift of about 13.3 kHz toward 1 ppm ethanol, while pristine WS2 showed almost no ethanol response from 1 to 100 ppm. This enhancement is likely caused by UV-induced defects and partially oxidized W-O/WOx-like sites, which promote ethanol adsorption and charge transfer.