Schottky nano-tip cathodes fabrication and diagnostics

The paper deals with a method for fabrication and diagnostics of microscopic cathode based on Schottky field emission. Schottky emission is considered to be the predominant electron source technology in actual focused electron beam equipment. For the ideal electron source, it is necessary to achieve following properties: small source size, low electron emission energy spread, angular intensity (an emission current per unit solid angle), low noise, long-term stability and a simple and low-cost operation. Electrochemical etching procedure, used for producing extra-sharp tungsten cathode tips, together with suitable noise based analysis method are presented in his paper. All of the cathodes were fabricated primarily for further experiments connected with the electron microscopy purposes. Noise diagnostics was performed on the cathode, under the ultra high vacuum conditions (UHV) in order to avoid environment interaction with ions which are present in the vacuum chamber. The noise spectroscopy in time and frequency domain is one of the promising methods to provide a non-destructive characterization of semiconductor materials and devices.