Fabrication and field emission characteristics of SnO2 electron sources based on planar-gate-type cathode arrays

An SnO2 electron source based on planar-gate-type cathode arrays was successfully fabricated by conventional photolithography, chemical wet etching and screen printing. A screen printing process was developed to deposit SnO2 field emitters onto the triode structure. An image of planar-gate-type field emission arrays (FEAs) with SnO2 field emitters were measured by the optical microscopy and scanning electron microscopy (SEM). The structure parameters and electric field strength distributions and trajectories of planar-gate-type triode were simulated by an ANSYS software. In addition, field emission characteristics of planar-gate-type triode with SnO2 field emitters were investigated. The experiment results show that the turn-on voltage of this triode structure at current density of 1 μA/cm2 is approximately 60 V. The anode current and gate current comes to 484 and 330 μA, at gate and anode voltages of 120 and 3000 V, respectively, and at the anode-cathode spacing of 2000 μm. Although the emission efficiency is modified from 72.7% to 59.3%, the luminescent uniformity and lightness of the fabricated cathode arrays obviously improve with the increases of gate voltage from 90 to 120 V. Moreover the emission current fluctuation was smaller than 15% for 15 h, which indicates that the fabricated device has a good field emission performance and long lifetime.