Fabrication and operation of triode electron emitters as ion source for miniature mass spectrometer

Abstract

We report the fabrication and operation of an ion source that can be incorporated into a micro-time-of-flight mass spectrometer. The ion source consists of an array of triode emitters with carbon-nanoparticle cathodes. We were able to extract an anode current as large as 94.3μA at a gate-bias voltage of 85V with a concomitant gate current of 38nA by using the triode structure having a recessed cathode with no gate overhang. Ion-generation tests with acetone molecules were carried out successfully, and we measured monotonic increases in the ion current and ratio between ion and electron currents with respect to acetone pressure. We also present simulation results that show equipotential and electric-field lines under different electrode-bias configurations.