SIMS Analyses of III-V Semiconductor Quantum-well and Superlattice Heterostructures

This work deals with the high-resolution SIMS characterization of sharp elemental distributions existing in quantum-well and superlattice structures. We have analysed III–V semiconductor multiple quantum-well and superlattice samples in order to derive useful information for the control of the growth procedure. A study of the depth resolution has been carried out with the purpose of achieving both highly depth-resolved and accurately calibrated profiles. High-resolution SIMS has been obtained by using low-energy primary ion beams. The better result has been found for InGaAs quantum wells embedded in GaAs, grown by metal organic chemical vapour deposition, for which decay lengths of 0.62 and 1.30 nm were measured at the leading and trailing edges, respectively, of the indium profile. The use of mathematical fitting procedures and the combined use of SIMS with other complementary techniques such as photoluminescence, x-ray diffraction and transmission electron microscopy, allows us to have an accurate method for the determination of layer parameters such as the thickness of a quantum-well, the position in depth and the element concentration. In addition, useful information on segregation and diffusion phenomena at the interface can be evidenced from the analysis.