CORRELATION BETWEEN CONTACT-ELECTRIFIED CHARGE GROUPS ON A THIN SILICON-OXIDE

Proximity effects of charge groups deposited by contact electrificatio n on thin silicon oxide in air were investigated using a modified atom ic force microscope. For initial separations L of L similar to 3.0 mu m, oppositely charged groups recede from each other in distance with t ime after contact electrification. On the other hand, a couple of nega tive (unipolar) charge groups approach each other with time. These fea tures are contrary to the expected approach or recession due to the Co ulomb attractive or repulsive forcer respectively. Furthermore, the cr itical time t(c) of a stable-unstable phase transition of negative cha rges becomes shorter or longer due to the proximity effects by the opp osite or same charge groups, respectively. These proximity effects see m to be induced by the interplay of the Coulomb force and the surface charge diffusion. (C) 1996 American Vacuum Society.