SIMS quantification of matrix and impurity species in Al xGa 1− xN

Abstract

The quantification in Al x Ga 1− x N with different AlN mole fraction ( x) is challenging because of matrix effects and charging effects. For quantitative characterization of both matrix and impurity elements in Al x Ga 1− x N, a novel charge neutralization method was employed and calibration curves were created using an O 2 + primary beam with positive secondary ion detection and a Cs + primary beam with negative and MCs + secondary ion detection. Over the range of 0 < x < 0.58, the matrix ion intensity ratios of Al +/Ga + and AlCs +/GaCs + appear linear with the mole fraction ratio x/(1 − x), and the ratio of AlN −/GaN − is linear with AlN mole fraction ( x). The sputter rate decreases as AlN mole fraction increases, while the relative sensitivity factors (RSF's) of impurities have an exponential relationship with AlN mole fraction. These calibration curves allow the quantification of both matrix and impurity species in AlGaN with varying AlN mole fraction. The technique can be employed for impurity control, composition and growth rate determination, as well as structural analysis of the finished optoelectronic and electronic devices.