Charge Distribution and Stability of SiO 2 Nanoarray Electret

The devices based on SiO 2 electret have significant applications in various MEMS sensors. However, the charge stability of SiO 2 electret suffered from the water percolation, which seriously restricts its application. In this work, the long‐term charge stability of the SiO 2 nanoarray electret (SiO 2 NAE) without any water repellent treatment is demonstrated. When the oxidation time is 1.5 h, the potential decay of the SiO 2 NAE is less than 46% during 60 days with an original potential of −120 V. The long‐term charge stability of the SiO 2 NAE is attributed to its unique charge decay process and the large H 2 O diffusion barrier in the SiO 2 NAE: firstly, the charge trapped in the planar part of the SiO 2 NAE decays rapidly. Then, residual charge stored in the SiO 2 nanoarray. Eventually, the large H 2 O diffusion barrier in the interface of Si/SiO 2 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.