Injection and Retention Characterization of Trapped Charges in Electret Films by Electrostatic Force Microscopy and Kelvin Probe Force Microscopy

Charge trapping memory has become a promising memory device due to its reliability, low cost, and simplicity. Its storage mechanism has attracted increasing attention. The properties of the storage layer are very important for the research of the device performance and mechanism. Herein, the technologies for the charge trapping properties of the storage layer are introduced first and then the study of charge trapping by electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) is reviewed. The properties of trapped charges for inorganic, polymers, nanomaterials, and organic small molecules are reviewed, when different experimental parameters such as the atmospheric moisture, injection time\bias, and hydrophilicity of films are used. The injection and retention mechanisms are also summarized.