Charge Distribution and Stability of SiO2 Nanoarray Electret

The devices based on SiO2 electret have significant applications in various MEMS sensors. However, the charge stability of SiO2 electret suffered from the water percolation, which seriously restricts its application. In this work, the long-term charge stability of the SiO2 nanoarray electret (SiO2 NAE) without any water repellent treatment is demonstrated. When the oxidation time is 1.5 h, the potential decay of the SiO2 NAE is less than 46% during 60 days with an original potential of -120 V. The long-term charge stability of the SiO2 NAE is attributed to its unique charge decay process and the large H2O diffusion barrier in the SiO2 NAE: firstly, the charge trapped in the planar part of the SiO2 NAE decays rapidly. Then, residual charge stored in the SiO2 nanoarray. Eventually, the large H2O diffusion barrier in the interface of Si/SiO2 effectively hinders the charge decay. In addition, we demonstrate the unique charge stability of nanoelectret, which has a promising application in developing high performance electret-based devices.