Cluster ion emission from nitrogen-doped GaAs and optimization of SIMS conditions for nitrogen analysis

Emission of “impurity-matrix” cluster ions from N-doped GaAs was studied using both Cs + and O 2 + ion bombardment and by monitoring positive and negative secondary species. Results of N depth profiling using different cluster ions were analyzed with regards to dynamic range, detection limit and depth resolution. Comparison of selected clusters exhibiting the best analytical parameters for each studied SIMS regime revealed that Cs + bombardment provides significantly better N detection limit than O 2 + bombardment. Under Cs + bombardment, the lowest detection limit was obtained by monitoring Ga 2N − clusters (11.5 keV impact energy), while the best depth resolution was obtained by monitoring CsN + clusters (2.5 keV impact energy). Cluster useful yield behavior and cluster energy spectra were analyzed, and it was concluded that a direct emission mechanism plays an important role in “impurity-matrix” cluster emission from N-doped GaAs matrix.