Compositional analysis of HgCdTe epitaxial layers using secondary ion mass spectrometry

The work reported here elaborates on the emission of the secondary Te⁻ ions from secondary ion mass spectrometry (SIMS) analysis of HgCdTe using a Cs⁺ primary ion beam. Investigations of numerous samples covering a wide compositional range showed excellent linear correlation between negative Te ion yield and Cd mole fraction. These led to the newly developed SIMS analytical method for measuring the changes in the composition of Hg_1−xCd_xTe with high sensitivity and depth resolution. A physical model describing the emission of secondary Te⁻ ions is proposed. The results can be interpreted by considering the short range interaction between reactive Cs primary beam and the CdTe sublattice via a ‘‘harpoon’’ mechanism. The relevance of this method to the development of Hg_1−xCd_xTe was demonstrated on metalorganic chemical vapor deposition grown heterostructures.