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

Germanium (Ge) and silicon (Si) 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 enlitters oxidzed at a greater rate than the positive polarity emitters. The negative polarity silicon emitters generated severall orders of magnitude greater particle emissions than any of the other emitters tested. The mean particle size was about 0.015μm. Although the germanium emitters oxidized, no evidence was found to indicate particles were shed from h s material. Preliminary data indcates the emitters perform equally well in Class 100 cleanroom air, and lowest particle generation is achieved when germanium electrodes are purged with dry air.