PREPARATION OF HIGHLY SENSITIVE AND STABLE GAS SENSING FILM BY USING HYDROTHERMALLY TREATED SEMICONDUCTING OXIDE COLLOIDAL PARTICLE

点击翻译按钮获取中文摘要

Thin film semiconductor gas sensors have been an intensive research target owing to their indispensable advantages such as high sensitivity, low fabrication cost and applicability for microsensors. Although there have been many attempts to fabricate thin-film sensors, none of them have been commercially available yet. It seems to be of key importance for a thin film device how the thin film can be fabricated uniform and kept stable during sensor operation. This study aims at establishing or evaluating hydrothermal treatment condition for SnOィイD22ィエD2 sol solutions, thermal growth behavior of SnOィイD22ィエD2 grains (crystallites) at elevated temperatures and gas sensing properties of the resulting this film device.1. Preparation of SnOィイD22ィエD2 sol by a hydrothermal treatment and grain growth behavior of hydrothermally treated SnOィイD22ィエD2A Hydrothermal treatment of α-stannic acid gel in ammonia water gives to a sol solution dispersing nanoparticle of SnOィイD22ィエD2 with a narrow particle si … More ze distribution (5 -7 nm). In addition, the SnOィイD22ィエD2 powder derived from the sol solution is very resistant to grain growth at evaluated temperature. This indicates that the thermal growth of crystallites is suppressed remarkably with the hydrothermal treatment. The suppression was more pronounced with decreasing SnOィイD22ィエD2 content of the sol solution, almost saturating at 1.8wt% sol content. It is seen that, at this content, crystallite size can be small as 13 nm after calcination at 900℃2. Gas sensing properties of thin film devices prepared from hydrothermally treated sol solutionsThis film SnOィイD22ィエD2 sensors were prepared from the hydrothermally treated sol solutions by a spin-coating method. This film devices proved higher sensitivity and quicker response transients compared with the conventional sintered-block type ones. These effects are expected to arise from a reduction in gas sensing layer thickness as well as smaller grain size. It was found that the HィイD22ィエD2 sensitivity decreased with an increase in film thickness. The CO sensitivity, on the other hand, was found to be almost independent on the film thickness. It seems that the observed difference in the thickness dependence reflects the difference in gas diffusion properties between HィイD22ィエD2 and CO through the micro pores of the film. Less