Development of the Scanning Atom Probe and Atomic Level Analysis

A scanning atom probe (SAP) was developed by modifying an ultrahigh vacuum scanning tunneling microscope. A unique feature of the SAP is the introduction of a funnel-shaped scanning microextraction electrode to a conventional atom probe. The electrode confines the high electric field required for field evaporation of the apex atoms in an extremely small space between the open hole of the extraction electrode and the apex of a micro cusp on a specimen surface. The incomparable capability of the SAP was successfully demonstrated by atom-by-atom analysis of microcusps of a thin diamond layer grown by chemical vapor deposition and microsilicon tips fabricated by a lithographic process. The study has shed light on the distributions and binding states of hydrogen in the diamonds and of oxygen and carbon in the silicon microtips for the first time.