Stable emission characteristics of nanometer-order size Transfer Mold field emitter arrays with in-situ radical treatment

Extremely stable, sharp, uniform, low operation voltage and nanometer-order size field emitter arrays (FEAs) have been developed by Transfer Mold fabrication method to realize reliable vacuum nanoelectric devices such as electric propulsion engines and environment-hard applications. Nanometer-order Transfer Mold Mo FEAs have been fabricated with the base lengths of 36-370 nm, which value of 36 nm is the smallest value ever reported. The emission fluctuations of Transfer Mold Mo FEAs without resistive layers and without in situ radical treatment, were ±1.6%, which is the lowest value ever reported. In this study, the field-emission characteristics of Transfer Mold FEAs have been evaluated by the in-situ oxygen radical treatment having the flux of 10¹⁵ atoms·cm^-2·s^-1, which is 10⁷-10⁸ times higher than typical fluxes experienced at the LEO. The emission fluctuations without resistive layer and with in-situ oxygen radical treatment were as low as ±4.5%, which is compared with 5-100% for conventional FEAs with resistive layers and without highly oxidizing atmospheres. The work functions (4.8-5.3 eV) of Transfer Mold Mo FEAs with radical treatment, which were calculated from slope of FN plot and the geometric factor, almost coincide with the work function (5.2 eV) measured from UPS. Thus, the Transfer Mold Mo FEAs have resistance to highly oxidizing environments, exhibiting very stable emission characteristics. Therefore, the Transfer Mold Mo FEAs can be used to make highly efficient and reliable vacuum electronic devices in harsh environments.