掺杂改善SnO_2甲醛气敏元件灵敏度特性的研究

用纳米SnO2制作了旁热式气敏元件。用掺杂方法提高SnO2甲醛气敏元件的灵敏度,掺杂剂包括Pd,Sb,Ti,Zr,Cu,Ag,Mn等。在SnO2气敏元件中分别掺杂质量分数2%Pd和2%Zr对提高元件灵敏度有显著效果。未掺杂SnO2、掺杂质量分数2%Pd和2%Zr的气敏元件对体积分数为5×10-5甲醛的灵敏度分别为1.33,2.38,2.08,但是掺杂在改善元件对乙醇的选择性方面作用不大。分析了掺杂改善SnO2气敏元件灵敏度的原理,当SnO2表面吸附还原性气体时,吸附气体提供电子,使半导体表层的导电电子数增加,引起电导率增加、电阻下降。吸附气体浓度越高,电阻率变化越大,元件灵敏度越大。

Research on Improvement of Sensitivity Characteristics of Doped-SnO_2 Formaldehyde Gas Sensor

Indirect-heat formaldehyde gas sensors were made of undoped nano-SnO2,and doped Pd,Sb,Ti,Zr,Cu,Ag and Mn into SnO2 respectively for improvement the sensitivity.The sensitivities of 2% Pd and 2% Zr-doped SnO2 sensors are much higher than that of undoped sensor.The sensitivities of undoped,2% Pd and 2% Zr-doped SnO2 sensors on 5×105 formaldehyde are 1.33,2.38 and 2.08 respectively.The selectivity of the sensors to ethanol can not be proved by doping.The mechanism of doped-SnO2 sensor was analyzed.Electrons are provided when reduction type gas is adsorbed on the surface layer of SnO2 and the electron on the surface layer of SnO2 increases,the conductivity increases and resistivity decreases.The higher concentration of adsorbed gas is,the more resistivity changes,and the higher sensitivity of the sensor is.