Analysis of bistable noise from microfabricated field emission cathodes

Field emission current fluctuations from microfabricated cathodes have been investigated. Time-correlated noise measurements and field emission electr on microscope images indicate that the dominant current fluctuations are bi stable in character and are emitted from a few localized sites on the catho de surface. Apertured bistable current transitions from these emission site s are often significantly larger than the percent change in total emitted c urrent. Analysis of bistable pulse lengths has shown that the dwell time in a particular bistable emission state decays exponentially with time. Curre nt autocorrelation measurements indicate that bistable noise at less than o r equal to 300 K is generated by adsorbates switching between emission stat es and not by adsorbate diffusion. (C) 2000 American Institute of Physics. [S0021-8979(00)01504-8].