Conduction invasion noise in nanoparticle WO₃/Au thin-film devices for gas sensing application

Abstract

Conduction noise measurements were carried out in the 0.3-45 Hz frequency range on Au films covered by a thin layer of tungsten trioxide (WO 3 ) nanoparticles. Exposing the films to alcohol vapor resulted in a gradually increased noise intensity which went through a maximum after an exposure time of the order of 15 min. The maximum noise intensity could increase by several orders of magnitude above the initial level. Longer exposure times made the noise decrease and approach its original value. This effect was not observed in the absence of WO 3 nanoparticles. The phenomenon is discussed in terms of a new 'invasion noise' model in which the noise is related to the insertion and extraction of mobile chemical species.

Gas sensor response of pure and activated WO3 nanoparticle films made by advanced reactive gas deposition

“…One part of the gas flow in the nanoparticle formation zone was diverted by the transfer pipe to the deposition chamber. This selection, and the fact that the gas flow is highly laminar, results in a narrow size distribution of the particles [15,16]. For producing the activated WO 3 nanoparticle films, additional Au or Al pellets were placed in the heating zone, thus resulting in co-evaporation or sublimation of the metallic dopant.…”

Electrochromic foil-based devices: Optical transmittance and modulation range, effect of ultraviolet irradiation, and quality assessment by 1/f current noise

“…Here we consider 1/f noise, where f denotes frequency, during the discharge of EC foil-type devices and with changes of this noise as a consequence of device degradation. 1/f noise has been used in the past for monitoring the reliability of electronic and ionic devices [13]; furthermore 1/f noise can give information on corrosion processes [47][48][49] and yield improved sensitivity in gas detectors [50][51][52].…”

Novel Applications of Noise in Sensing and Communications

“…To generate a separate pattern corresponding to different chemical compositions, a number (6 to 40) of different types of sensors are needed, which makes the system expensive and unreliable for practical applications. On the other hand Fluctuation-Enhanced Sensing (FES) (see Figures 1,2) is able to generate a complex pattern by the application of a single sensor [1][2][3][4][5][6][7][8][9].…”

“…In 2001, Smulko et al were the first to use higher-order statistics to enhance the extracted information from the stochastic signal component [8,13,14]. Hoel et al showed FES via invasion noise effects at room-temperature in nanoparticle films [9]. Schmera and coworkers analyzed the situation of Surface Acoustic Wave (SAW) sensors and predicted the FES spectrum for SAW and MOS sensors with surface diffusion [10][11].…”