DETERMINATION OF ALXGA(1-X)AS COMPOSITION - THE MBE PERSPECTIVE

Although the AlxGa(1-x)As alloy system has been extensively investigat ed, there are still considerable uncertainties in measuring the value of x. Here a new AlxGa(1-x)As calibration structure, grown by molecula r beam epitaxy, has been used to establish unambiguous alloy compositi ons. Such 'standard' AlxGa(1-x)As layers were measured by high-resolut ion X-ray diffraction, photoluminescence, and Raman spectroscopy to de termine the compositional variations of the measured physical paramete rs. The formulae provided give a reliable calibration base for other c haracterization tools. A detailed analysis of the X-ray results shows that Vegard's law does not hold fur the variation of the AlxGa(1-x)As lattice constant with x.