Abstract: A surface voltage sustaining structure around an n.sup.+ (or p.sup.+)-type region on a p.sup.- (or n.sup.-)-type substrate for high-voltage devices is made by a combination of n-type regions and/or p-type regions and produces an effective surface density of donor (or acceptor) decreasing with the distance to the n.sup.+ (or p.sup.+)-type region on the surface, when all of the regions are depleted under reverse breakdown voltage. The surface voltage sustaining structure can make the breakdown voltage of the n.sup.+ -p.sup.- (or p.sup.+ -n.sup.-)-junction reach more than 90% of that one-sided parallel plane junction with the same substrate doping concentration. High-voltage vertical devices as well as high-voltage lateral devices with fast response, low on-voltage and high current density can be made by using this invention.