Comparison of germanium and silicon needles as emitter electrodes for air ionizers

Abstract Germanium and silicon needles were tested as emitter electrodes for use in low-particle-generating static eliminators. The materials were found to oxidize with minimal incorporation of nitrogen, and the negative polarity emitters oxidized at a greater rate than the positive polarity emitters. The negative polarity silicon emitters generated several orders of magnitude greater particle emissions than any of the other emitters tested. The mean particle size was about 0.015 μm. Although the germanium emitters oxidized, little evidence was found to indicate particles were shed from this material. Preliminary data indicates the emitters perform equally well in Class 100 cleanroom air, and lowest particle generation is achieved when germanium electrodes are purged with dry air.