a portion of the electrode adjacent the exposed surface of the electrode first modified electrode material 270 is selected to have a tcr with little or no change with positive temperature change so that at programming temperatures of 600 u00b0 c or more the resistivity of first electrode material 270 does not decrease to a value lower than a resistivity at a reduced non programming temperature in one example electrode material 270 has a resistivity r 1 that is higher than a resistivity r 2 of electrode material 230 a at temperatures greater than 600 u00b0 c or at least has a thermal coefficient of resistivity that has a lower variation to positive temperature change modifying species 260 of oxygen carbon or nitrogen when introduced into polycrystalline silicon to form electrode material 270 has shown a reduced tcr compared to polycrystalline silicon with electrode material 270 having a greater resistivity r 1 at 600 u00b0 c to 650 u00b0 c than electrode material 230 a of polycrystalline silicon the amount depth of the first electrode material 270 generally depends on the amount of voltage that will be used to set or reset a volume of memory material using voltages in the range of about 3 3 volts v according to current technology a suitable depth for electrode material 270 of for example sic or sio 2 into a polycrystalline silicon electrode is approximately 600 angstroms u00e5 at lower voltages a shorter depth would be suitable in terms of amount of first electrode material 270 amounts of 0 1 to 20 atomic percent of modifying species 260 are suitable 0 5 to 10 percent are.