Design for ultra sensitive oxide semiconductor gas sensor by controlling meso-pore and high order structure

介孔和高阶结构控制超灵敏氧化物半导体气体传感器设计

基本信息

批准号：
13450354
负责人：
YAMAZOE Noboru
金额：
$ 9.54万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13450354/
关键词：
Semiconductor gas sensor High order structure Mesopore Macropore SnO_2 Gas diffusion Grain size Hydrothermal treatment 一次粒子径二次粒子径拡散方程式酸化スズ

项目摘要

Recently, numerous kinds of gases are emitted from various origins into our living space, working space or outdoors. Many of them, like air pollutants and VOCs (volatile organic compounds), are hazardous to human beings and environments. Most of these gases are present at low concentrations so that extremely good sensing characteristics are requested for their monitoring. It seems imperative to establish sensor design principles on the basis of fundamental understandings of semiconductor gas sensors. In this research project, the influences of gas transport on the gas sensing properties of semiconductor gas sensor are investigated theoretically, based on the diffusion equation assuming Knudsen diffusion and first order surface reaction of a target gas. The followings are found to be important factors in order to realize such high sensitive gas sensors by theoretical study(1) Control of mesopores where competition between gas diffusion and surface reaction takes place.(2) Control of size of the secondary particles involving mesopores.(3) Control of macropores through which gas diffusion is rapid.The followings are also found in this research project.(1) Crystallite size of SnO_2 could be enlarged and controlled in the range from 6 nm to 12 nm by controlling preparation procedure of stannic acid gel and hydrothermal treatment conditions.(2) SnO_2 could be coated thinly on SiO_2 spherical particles by adjusting pH.(3) Large size pores could be introduced into thin film of SnO_2 by mixing organic reagent.Besides, aqueous sols of tungsten oxide dehydrate could be prepared by an ion-exchange method. The size of the crystallites could be controlled by washing, centrifugal treatments and/or ultrasonic agitation of the sol, providing a method to control the crystallite size. It was also found that thick film device derived from tungsten oxide dehydrate sol gave an extremely high sensitivity to NO_2.

近年来，多种气体从不同的来源排放到我们的生活空间、工作空间或室外。其中许多污染物，如空气污染物和 VOC（挥发性有机化合物），对人类和环境有害。大多数这些气体的浓度较低，因此对其监测需要极好的传感特性。在对半导体气体传感器的基本理解的基础上建立传感器设计原则似乎势在必行。在本研究项目中，基于假设目标气体的努森扩散和一级表面反应的扩散方程，从理论上研究了气体传输对半导体气体传感器气敏特性的影响。通过理论研究发现以下是实现这种高灵敏度气体传感器的重要因素(1)控制气体扩散和表面反应之间发生竞争的中孔。(2)控制涉及中孔的二次粒子的尺寸。 (3)控制气体快速扩散的大孔。本研究项目还发现:(1)通过控制SnO_2的制备过程,可以将SnO_2的晶粒尺寸放大并控制在6 nm~12 nm范围内。锡酸凝胶和水热处理条件。(2)通过调节pH值可以将SnO_2薄薄地包覆在SiO_2球形颗粒上。(3)通过混合有机试剂可以在SnO_2薄膜中引入大尺寸的孔。此外,氧化钨水溶胶脱水物可以通过离子交换法制备。微晶的尺寸可以通过溶胶的洗涤、离心处理和/或超声搅拌来控制，从而提供了控制微晶尺寸的方法。还发现由氧化钨脱水溶胶衍生的厚膜器件对NO_2具有极高的灵敏度。