HIGH-RESOLUTION DEPTH PROFILING OF INXGA1-XAS GAAS MULTIPLE-QUANTUM-WELL STRUCTURES BY COMBINATION OF SECONDARY-ION MASS-SPECTROMETRY AND X-RAY-DIFFRACTION TECHNIQUES/

In this work we investigate multiple quantum well semiconductor struct ures by secondary ion mass spectrometry (SIMS) and high-resolution x-r ay diffraction measurements. The combined use of these techniques turn s out to be a very powerful tool for an accurate investigation of both structural and chemical characteristics of complex structures consist ing of thin alternating layers. We show that the x-ray data allow us t o increase the accuracy of the SIMS analyses providing internal standa rds, for both depth scale and concentration calibration. This procedur e allows us: (i) to determine accurate quantitative SIMS concentration profiles which lead to the determination of the elemental concentrati on in the quantum wells, (ii) the mole fraction and layer thickness of embedded layers, and (iii) also to investigate eventual segregation a nd diffusion phenomena occurring at the interfaces. Our procedure is d emonstrated on a set of InxGa1-xAs/GaAs multiple quantum well structur es grown by metalorganic chemical vapor phase epitaxy. The experiments , performed by secondary ion mass spectrometry and high-resolution x-r ay diffraction measurements, as well as the methodology of the data an alyses are discussed in detail. As the main result of our investigatio n we obtained the precise indium distribution in each of the investiga ted samples with an accuracy below 5% and the individual barrier and w ell layer thickness. (C) 1997 American Vacuum Society.