High efficiency ZnO nano sensor, fabrication and characterization

Abstract

Ultra fine thin films of pure and SnO doped ZnO nanosensor were grown on gold digitated ceramic substrate from bis(2, 4-pentanedionate)dimethylethanolamine zinc (II) using bis(2, 4-pentanedionate) tin(II) chloride as a dopant by ultrasonic aerosol assisted chemical vapor deposition technique (UAACVD) at temperature range of 400-450 °C under oxygen atmosphere at 5 Pa pressure. The sensitivity, selectivity, fast recovery, and reliability test performed on nanosensor suggested that both doped and undoped ZnO thin films are suitable for detecting ethanol vapor in the temperature range of at 60 to 150 °C, whereas at room temperature (25 °C ) response and recovery time of the sensor increases many folds compared to 60 °C. Sensitivity of the ZnO sensor shows linear relationship with the increase of gas concentration. Electrical properties show that 1 % SnO doped ZnO enhanced the sensitivity of the film drastically and thus improved its detecting efficiency. Physico-chemical techniques like, CHNS-O, atomic absorption analyzer, and infra red and multinuclear nuclear magnetic resonance spectrometers were used for precursor characterization. X-ray diffractometer, scanning electron microscope, sigma scan analyzer and energy dispersive x-ray techniques were used for thin film characterization.

ZnO Rods with Exposed {100} Facets Grown via a Self-Catalyzed Vapor–Solid Mechanism and Their Photocatalytic and Gas Sensing Properties

“…Other reports, in contrast, reveal opposite behavior, with our microsensors showing almost 2 or 32 times lower responses than those recorded for thermoactivated {001} facets, or a response nearly similar to that reported for {42̅3̅} facets (a more reactive surface compared to {100} or {001} surfaces) . A similar comparison with other ZnO morphologies including films, , particles, wires, , or comb-like structures (with no references to their dominant exposed facets) indicates improved photo- and thermoactivated responses for our microsensors toward C 2 H 6 O and CO (Figures S7 and S8, Supporting Information). Consequently, it is complex to attribute any improvement exclusively to the dominant exposed facets, as the fabrication and test conditions used in each work also impact the sensor performance; particularly the direct integration of structures into the device via AACVD (as opposed to most of the cited works which rely on transfer methods to integrate the sensitive material) provides cleaner surfaces that could favor the gas sensing properties of the ZnO rods.…”

“…The sensitivity of ZnO toward analytes such as CO, C 2 H 6 O, C 7 H 8 , and NO 2 was reported in the literature previously, − although only a few works described the correlation of the exposed facets with the sensor response in “real” devices, and often only to C 2 H 6 O. Generally, these works suggest that the {100} facets are the most stable surfaces in ZnO, providing long-term stability advantages to this sensitive material particularly when using thermoactivation, , but due to the presence of fewer dangling bonds in {100} facets, as opposed to other facets, e.g., {001} or {42̅3̅}, the {100} facets have shown consistently less sensitivity. − The present work, however, has not experimentally proven gas sensing properties of other ZnO facets, and comparison of our results with the literature (Table ) shows conflicting conclusions.…”