Efficient surface-conduction field emission electron sources from tin oxide film

This paper describes a study on the surface-conduction field emission (SCFE) electron sources based on island-like tin oxide (SnO2) film by magnetron sputtering, conventional photolithography and lift-off method. The images of island-like SnO2 film were characterized by the optical microscopy and atomic force microscopy (AFM). Field emission (FE) characteristics of SCFE electron sources with SnO2 film were also investigated. The AFM images show that the diameter of island-like SnO2 film is approximately 100-300 nm and the gap of most island-like SnO2 film is around 10-30 nm. FE properties reveal that the emission current and conducted current are completely controlled by gate voltage. The electron emission efficiency is around 0.95% when the anode voltage and gate voltage was fixed to be 3.2 kV and 238 V, respectively, at the anode-cathode gap of 500 μm. The emission images obviously become brighter and more uniform with the increases of the gate voltage and the maximum brightness can reach 850 cd/m2. The emission current fluctuation is smaller than 5% for 4 h, which indicated that the fabricated electron sources have an efficient field emission performance.