This invention provides a method or an auxiliary method to implement optimum variation lateral flux on a semiconductor surface. The method is to cover one or more thin films of high permittivity dielectric material on the semiconductor surface. The one or more films are capable of transmitting flux into or extracting flux from the semiconductor surface, or even to extract some flux from a part of the semiconductor surface and then transmit the flux to another part of the semiconductor surface. By using optimum variation lateral flux, not only can high-voltage lateral devices be made, but also an edge-termination technique for high-voltage vertical devices is provided. While the thin films can be used to prevent the occurrence of strong electric fields produced at the edges of some doped regions, these regions are used to compensate other doped regions with opposite doping and different location. Thin films can also be used to realize an optimum variation lateral flux of a lateral semiconductor device, which is located on a substrate and the flux flowing between the semiconductor and the substrate is negligibly small.