Fluctuations of Field Emission Currents under Extreme High Vacuum

We report the result of the noise measurement using an extreme high vacuum field emission microscope (XHV-FEM) operating under ∼ 7 × 10-10Pa. The fluctuation of a field emission (FE) current for a clean W(111) tip was comparable to the corresponding shot noise fluctuation, demonstrating the suitability of the XHV-FEM for investigation on the inherent fluctuation behavior of the FE process. Semilogarithmic damping curves of FE currents were linear for more than 10 hours. The noise of field emission (FE) currents ranging from 10 pA to 100 μA was measured under ∼ 7 × 10-10Pa. The lowest frequency measurement of shot noise was recorded at below 10 Hz. [DOI: 10.1380/ejssnt.2008.64]