Field Emission from Whiskers

Abstract

A method for obtaining field emission from whiskers grown in situ from the vapor under high-vacuum conditions has been developed and is described. It is possible to fabricate clean and strong emitters from almost any conducting material, so that the range of substances that can be used for field emission has been considerably expanded. Electrical methods for following the growth kinetics and determining whisker length and radius are described and applied to Au. Growth is found to be positively exponential with time, which supports a mechanism of growth by diffusion of impinging atoms over the whisker sides and incorporation at the growing end. Cessation of growth is diffusion limited in these experiments. It was possible to estimate the activation energy for the surface diffusion of Au on Au as 23±5 kcal from the variation of terminal length with temperature. Some adsorption and oxidation experiments indicate that the method can also be used for the study of these phenomena. It was found for instance that H2 is not adsorbed on Au and that Al is oxidized with severe surface rearrangement even at 77°K.