A CONTRIBUTION TO THE SEARCH FOR A STABLE FIELD-EMISSION ELECTRON SOURCE BASED ON W-WOX-AU AND W-AL2O3-AU SYSTEMS

Field emission properties of metal-oxide-metal (MOM) cathodes (W-Wo(x) -Au and W-Al2O3-Au) were investigated experimentally as potential cold point source of electrons for high resolution microscopes, spectrosco pies and possibly also for pressure measurements in UHV. The stability as well as recovering problems were studied for the operation of thes e cathodes in presence of various gases (H-2, He, Ne, Ar, CO, N-2). Th e effect of pressure up to 10(-6) mbar has been investigated. Tentativ e interpretation of the observed phenomena based on resonant tunneling through a double barrier system has been demonstrated together with a simple procedure (mild heating to red glow) for recovery of the initi al emission current, which was lowered beforehand by operation of the cathode in pressure of gases with higher molecular weights (CO, O-2, N -2, Ar). The negligible effect of the chemical nature of molecules as well as of low-molecular weight gases (H-2, He) onto the emission curr ent has been demonstrated. (C) 1998 Elsevier Science Ltd. All rights r eserved.