The Influence of Quartz Resonator Design and Thin Metal Oxide Layers on QCM Parameters

摘要

Quartz resonators and thin metal oxide sorption layers are the main elements of quartz crystal microbalances (QCM). Quartz resonators, AT cut with basic frequency of 16 MHz, dynamic resistivity below 20 Ω and quality factor around 50 000 have been developed. Thin layers of SnO_2 and MoO_3 are used as sensing films. The influence of sorption layers on quartz resonator parameters with different electrode configurations is studied. The change of the spectral characteristics and dynamic parameters is traced. Quartz resonators with SnO_2 and MoO_3 (200 nm) sensitive layers are investigated at NH3 concentrations from 10 ppm to 1000 ppm. Quartz resonators with Au electrodes (with a diameter 3, 4 and 5 mm) are compared. At both sorption layers the highest sensitivity corresponds to quartz resonators with Au electrodes with a diameter of 4 mm. The fabricated structures can be used as sensor elements in QCM.