Charge storage in plasma deposited thin films

The authors describe the production of electrets prepared at ambient temperature in a dual-mode microwave/radiofrequency plasma reactor on single-crystal silicon substrates. They consist of 0.5-1.5-μm-thick films of plasma silicon dioxide, plasma silicon nitride, plasma polymerized hexamethyldisilazane (pp-HMDSN), or a multilayer structure of these materials. The electret characteristics can be controlled by varying the plasma parameters and by a subsequent heat treatment, followed by a HMDSN-vapor surface modification. In order to characterize the charge storage capability, the samples were positively or negatively corona-charged and the charge decay was observed by measuring the surface potential at different temperatures. In addition, thermally stimulated current spectra were measured to obtain information about the activation processes