DC electrical breakdown of water in a sub-micron planar gap

Water breakdown subjected to uniform DC electric field in 300 nm planar gaps is experimentally studied. Test devices with microstrip line configurations are fabricated through nanofabrication technology and the results show that water breakdown occurs at ~ 100 kV/cm electric field under current system setup. The initiation process of water breakdown in a small gap is discussed. It is most likely being initialized by pre-existed bubbles or bubbles generated from electrolysis of water. Electrode surface roughness is examined and its effect on observed water breakdown is investigated. Therefore, the process for electrode fabrication needs to be carefully chosen and the fabrication procedures need to be optimized to provide smooth surfaces without sharp tips or micro protrusions in future water breakdown investigations.