Charge distribution in thin inorganic electret layers

The space charge distribution in solid dielectrics can generally be measured by several nondestructive techniques such as the Laser Induced Pressure Pulse (LIPP), the Piezoelectrically Induced Pressure Step (PIPS) and the Thermal-Pulse (TP) methods. The application of these methods improves the understanding of charging processes in electrets. With the expanding field of micromachined sensors and actuators the interest in inorganic electret layers which are compatible to silicon technology is growing. SiO₂ has already proved very good electret properties and has already been used in several applications such as integrated microphones. In this experiment the thermal-pulse method is applied to thermally wet grown silicon dioxide layers. Experimental results are reported and discussed briefly