화학공학소재연구정보센터
Journal of Vacuum Science & Technology B, Vol.13, No.6, 2441-2444, 1995
Field-Emission Properties of Self-Shielded Tungsten Sources
The electron emission properties of self-shield W tips were studied by field emission microscopy and spectroscopy. Self-shielded tips were formed by focused ion beam milling an annular depression on the apex of an electrochemically etched W[111] tip. The resultant tip structure consists of a flat bottomed crater (the outer rim of which forms the shielding electrode) with a central protrusion (the emitter). In situ processing consisted of moderate thermal flashing and partial buildup. Significantly greater angular emission current densities were measured, as compared to both unshielded W[111] built-up tips and standard W[310] tips. Energy analysis of the emitted electrons showed no deviations from normal W[111] emission. Self-shielding may offer a generally applicable method for increasing the brightness of field emission sources in a variety of electron optical instruments.