Characterization of the tunneling insulator in MIM cathodes by low-stress I-V measurement

The low-stress current-voltage (I-V) measurement system was developed and applied to characterization of the insulator in metal-insulator-metal (MIM) tunneling cathodes. The amount of the total charges injected into these devices during the I-V measurement decreases by four orders of magnitude compared to that for the conventional measurement system. The developed I-V measurement, therefore, can be considered to be a damage-free characterization method. The time-reciprocal dependence of the transient current demonstrates that the low-voltage leakage current (LVLC) of an MIM cathode is a good measure of the trap density in the tunneling insulator. The LVLC measurement was used for monitoring the plasma process-induced damage and long-term degradation of MIM cathodes. The charging damage during the sputter-deposition process was reduced to an acceptable level by modifying the sputtering machine and designing the device layout pattern properly according to antenna ratio. A long-term operation experiment showed that the low-stress I-V measurement can detect the latent degradation of insulator quality. The developed I-V measurement is thus considered to be a useful tool that will lead to improvements in device performance and lifetime.