  Plasma profiling time of flight mass spectrometry (PP-TOFMS) has recently
gained interest, as it enables the elemental profiling of semiconductor
structures with high depth resolution in short acquisition times. As recently
shown by Tempez et al., PP-TOFMS can be used to obtain the composition in the
structures for modern field effect transistors [1]. There, the results were
compared to conventional SIMS measurements. In the present study, we compare
PP-TOFMS measurements of an Al-/In-/GaN quantum well multi stack to established
micro- and nano-analysis techniques like cathodoluminescence (CL), scanning
transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy
(EDX) and X-ray diffraction (XRD). We show that PP-TOFMS is able to resolve the
layer structure of the sample even more than 500 nm deep into the sample and
allows the determination of a relative elemental composition with an accuracy
of about 10 rel. %. Therefore, it is an extremely rapid alternative method to
obtain semiconductor elemental depth profiles without expensive and time
consuming sample preparation as it is needed for TEM. Besides, PP-TOFMS offers
better depth resolution and more elemental information than for example
electrochemical capacitance-voltage (ECV), as the acquisition of all elements
occurs in parallel and not only electrically (ECV) or optically (CL) active
elements are observed.
