Atomic level analysis of electron emitter surfaces by the scanning atom probe

Fine grains of chemical vapor deposition (CVD) diamonds and silicon tip ape xes of a microtip array are mass-analyzed at atomic dimension by a scanning atom probe (SAP). The study revealed that the CVD diamonds contain a large amount of hydrogen, which is field-evaporated as carbon-hydrogen cluster i ons, Some hydrogen atoms are weakly bound with the carbon-hydrogen clusters by hydrogen bonding and are released from the clusters while flying from t he diamond surface to the detector. The depth profile of the hydrogen distr ibution indicates that hydrogen concentration decreases logarithmically wit h depth. The analysis of the silicon tip apex also revealed that the tip ap ex contains a significant amount of carbon and hydrogen. The silicon-carbon ratio of the uppermost surface layer is as high as 1:1 and rapidly decreas es with depth and approaches nearly 2% at a depth of 20 nm. This suggests t hat the carbon might be intermixed or absorbed during the fabrication and/o r dry etching process of the microtip array. (C) 1999 Elsevier Science B.V. All rights reserved.