seen in the graph of fig3 this figure is explained in more detail below typically the substrate injection currents are reduced by from about 17 to about 3 when the cathode body and isolation are at the same potential it reduces to about 0 5 when isolation potential is 5 volts higher than the body it will be readily apparent to one of skill in the art who has read this disclosure and reviewed the drawings that there are a variety of ways to make the isolated zener diodes of the present disclosure one example will be explained with the understanding that other methods with modifications and variations within the scope of knowledge of a person of ordinary skill in the art are within the scope of the appended claims referring to fig2 and 4 where fig4 depicts schematically a method 300 of making an example of an isolated zener diode a p type substrate layer 110 is formed in block 310 an optional epitaxial layer pepi 1 120 is formed over layer 110 in block 320 after layer 120 is formed layers 130 and 140 may be formed either in sequence or simultaneously in block 330 layer 130 may be formed by ion implantation followed by diffusion and annealing for example after formation of layer 130 and region 140 region 165 p epi is formed in block 340 this may be followed by implantation for regions 150 195 190 180 170 and or 160 with appropriate n and p types in block 350 alternatively after formation of layer 130 and region 140 region 165 is formed followed by n type.