New Cluster Secondary Ions for Quantitative Analysis of the Concentration of Boron Atoms in Diamond by Time-of-Flight Secondary-Ion Mass Spectrometry

Abstract

A new approach to quantitative analysis of the concentration of boron atoms in diamond using secondary- ion mass spectrometers with time-of-flight mass analyzers is proposed. Along with the known boron-containing lines (B, BC, BC₂), many lines related to cluster secondary ions BC_N have been found in the mass spectrum; their intensity increases by one or two orders of magnitude when Bi₃ probe ions are used. Lines BC₄, BC₆, BC₂, and BC₈ have the highest intensity (in the descending order); when they are summed, the sensitivity increases by an order of magnitude in comparison with the known mode of detecting BC₂. The parameters of the boron δ-layer in single-crystal diamond films grown under optimal conditions have been measured to be unprecedented: the δ-layer width is about 2 nm, and the concentration is 6.4 × 10²⁰ cm^–3 (the boron concentrations for doped and undoped diamonds differ by four orders of magnitude).