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非晶态二氧化硅 (SiO2 )具有优良的驻极体性质 ,可制成微型化、集成化和机敏化的高灵敏度的传感器。但是 ,热氧化SiO2 驻极体膜的高压应力引起微结构变形 ,对薄膜储电特性形成复杂的影响。利用氮化硅薄膜的高张应力研制成氮化硅 /二氧化硅 (Si3 N4 /SiO2 )双层膜 ,可使其内应力相互补偿。本文讨论了双层膜驻极体的电荷储存稳定性及电荷输运特性。实验结果表明 ,Si3 N4 /SiO2 双层膜具有比单层膜更优异的电荷储存稳定性 ,Si3 N4 /SiO2 双层膜系统的电荷寿命比SiO2 驻极体约高两个数量级。常温恒压电晕充电 ,电荷被储存在Si3 N4 /SiO2 双层膜的近自由面附近 ,随着充电温度的提高 ,平均电荷重心向驻极体内部迁移。但是在低于 3 0 0℃的充电温度下 ,平均电荷重心不能达到Si3 N4 和SiO2 的界面处。电荷输运受缓慢再捕获效应控制。
Amorphous silica (SiO2) has excellent electret properties and can be made into a miniaturized, integrated and highly sensitized sensor. However, the high-pressure stress of the thermal oxide SiO2 electret film causes the deformation of the microstructure, which has a complicated influence on the film storage characteristics. Silicon nitride / silicon dioxide (Si3N4 / SiO2) bilayer films are developed by using the high tensile stress of silicon nitride films to compensate their internal stresses. This paper discusses the charge storage stability and charge transport properties of bilayer membrane electrets. The experimental results show that the Si3 N4 / SiO2 bilayer membrane has more excellent charge storage stability than the monolayer membrane, and the charge life of the Si3 N4 / SiO2 bilayer membrane system is about two orders of magnitude higher than that of the SiO2 electret. Constant voltage corona charging, the charge is stored near the free surface of the Si3 N4 / SiO2 bilayer membrane, with the charging temperature increases, the average charge center of gravity to the electret migration. However, at charge temperatures below 3000C, the average charge center of gravity can not reach the interface of Si3N4 and SiO2. Charge transport is controlled by slow recapture effect.