QUANTITATIVE DEPTH PROFILING RESONANCE IONIZATION MASS-SPECTROMETRY OF GAAS/ALGAAS HETEROJUNCTION BIPOLAR-TRANSISTORS

Resonance ionization mass spectrometry of neutral atoms sputtered from GaAs/AlGaAs materials, used for heterojunction bipolar transistors (HBT), provides quantitative information about the dopant position near interfaces. The results help elucidate beryllium dopant migration because they are free of matrix effects common in secondary ionization mass spectrometry. HBT performance is shown to be associated with Be location. Quantitative analysis of Be is possible across the AlGaAs/GaAs interface without extensive use of standards. The magnitudes of dopant (Be) and matrix (Al) signals are related in proportion to their concentration.