Secondary Electron Emission from MgO Thin Films

Abstract

MgO thin films have been prepared and their secondary electron emission properties examined using both single pulse and dc measurement methods. High yields in the range of 15–20 are observed. The films are crystalline with an average crystal diameter of 100–500 A, comparable to the escape depth of the secondaries. The high yields are found to result primarily from the properties of bulk crystalline MgO rather than from thin film phenomena. Field enhanced emission is however observed and has been found to enhance the yield under some conditions by as much as 20%. The most probable energy of emission of the secondaries is about 1 ev. The yield of the films decreases upon exposure to water vapor and carbon dioxide. The films are found to be fairly stable under electron bombardment.