distribution within conductors is usually not practical. However, for insulator electrets carrying neat charges, the charges could be kinetically immobilized for a relatively long time in any position inside the insulator due to the high electrical resistance, while the electric field and charge density inside the electret are not kinetically zero. [1][2] Insulators could trap charges from the external electrical or photonic stimulus, referring to electrets, which are being developed for transistors, memories, and bio-mimic systems. [3][4][5][6][7][8][9][10][11][12] However, as compared with electrical conductors, insulators intrinsically have high electrical resistance, thus the charge injection and release typically require high voltage or long applied duration, which limits their applications in highspeed devices. [13] Nanocomposites [14][15][16] or floating-gate [17][18] architectures have been developed to improve the charge storage and release capability, which has been commercially applied for memory applications. The community is looking for new strategies to further tune the charge storage and release dynamics for advanced electronic and photonic applications. [6][7][19][20][21] Plasma, generated by electrical discharge, contains ionic or radical species and could interact with materials. Recently, plasma has been employed to etch materials for academic and industrial applications. Additionally, appropriate plasma treatment could potentially induce polar groups and thus electronic trap sites at the surface of the materials. [22][23][24] For instance, oxygen plasma-treated SiO 2 dielectric is used to generate polar trap sites to tune the performance of field-effect transistors. [25][26][27] However, the trap density on the surface of the inorganic materials is difficult to be satisfactorily manipulated within a large range by conventional plasma treatment, while this plasma treatment is applicable for only a few materials. On the other hand, as compared with inorganic materials, organic semiconductors or insulators usually interact with plasma species more fiercely. Conventional plasma could, unfortunately, deteriorate the etched materials, not only at the surface but also tens of nanometers away underneath the surface, which consequently damages the materials. [28] Recently, it is reported that soft plasma can be carefully generated by glow discharge at Insulator materials can trap charges, referring to electrets, which are attractive for transistors and memories. However, insulators intrinsically exhibit high electrical resistance, thus the charge injection and release inside insulators typically need high voltage or long bias time, limiting the applications that require high writing/erasing speed. In this work, insulator polymer polystyrene (PS) film is treated by a soft plasma, which selectively induces a high density of charge traps at the top surface, without changing the electronic properties of the underneath materials. The thus-prepared surface is easily occupied by external neat charges to form ...