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

Fine grains of chemical vapor deposition CVD.diamonds and silicon tip apexes 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 ions. Some hydrogen atoms are weakly bound with the carbon–hydrogen clusters by hydrogen bonding and are released from the clusters while flying from the diamond surface to the detector. The depth profile of the hydrogen distribution indicates that hydrogen concentration decreases logarithmically with depth. The analysis of the silicon tip apex also revealed that the tip apex 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 decreases with depth and approaches nearly 2% at a depth of 20 nm. This suggests that the carbon might be intermixed or absorbed during the fabrication andror dry etching process of the microtip array. q1999 Elsevier Science B.V. All rights reserved