Effects of gases on the field emission performance of silicon gated field emitter array

Effects of gases on field emission performance were measured using silicon-gated field emitter arrays. Gas was injected into a vacuum chamber with a 1000 × 1000 tip array, which was driven by a DC gate and collector voltages. The collector voltage was fixed at 200 V while the gate voltage was swept to 40 V. For the gas exposure study, N₂, He, and Ar were used. The sets of partial pressures, 5 × 10⁻⁶, 5 × 10⁻⁵, and 5 × 10⁻⁴ Torr, were used for the experiment. It was observed that N₂ had the least effect and Ar had the worst effect on emission current performance. The degradation of collector current at 5 × 10⁻⁴ Torr pressure for Ar was ≈65% where for the N₂, at the same level of pressure, the degradation was ≈41%. However, further experiments with high purity Ar gas showed that it was the water vapor present in the gas itself that was the primary cause of reduction in emission current and not the gas itself. The results expressed in reduction in emission current versus Langmuir exposure versus the current clearly showed the effect of water vapor. After the vacuum was recovered, the work function again restored partially to its original value. After ultraviolet light cleaning, the emission current was restored completely to the original state.