Matrix effect and surface oxidation in depth profiling of AlxGa1−xAs by secondary ion mass spectrometry using O+2 primary ions

Abstract

The dependence of the ionization probability in secondary ion mass spectrometry experiments of the dopants Be, Ge, and Sn and the matrix atoms Ga and As in Al_xGa_1−xAs with 0≤x≤0.83 on the matrix composition is determined using O⁺₂ primary ions. The composition of the surface is analyzed for the first time by Auger electron spectrometry during O⁺₂ bombardment. The ionization probability shows an approximately linear increase with increasing Al content ranging from a factor of 2.5 (for Ga⁺) to 7.5 (for Ge⁺). The variation of the ionization probability is a function of the degree of oxidation which depends on the metal‐oxygen bond energy and on the availability of oxygen. The availability of oxygen is controlled by the implantation sputtering process during O⁺₂ bombardment.