Comprehensive analysis of the composition determination in epitaxial AlxGa1-xAs films: A multitechnique approach

Abstract

We present the determination of aluminum concentration x in epitaxial films of AlxGa1-xAs grown by Molecular Beam Epitaxy (MBE) on GaAs (100) substrates. A large variety of techniques such as quantification of atomic fluxes during MBE growth, high resolution X-ray diffraction (HRXRD), X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray spectroscopy (EDS), variable angle spectroscopic ellipsometry (VASE), photoluminescence (PL) and Raman spectroscopy (RS) have been used. Our Raman spectroscopy measurements show inconsistencies when analyzed with previously reported models. We also found variability within the same sample indicating that it is strongly influenced by other parameters like strain. We conclude that Raman spectroscopy can not be used as a reliable characterization technique without taking these effects into consideration. The combined analysis of all the other techniques allows us to reduce the uncertainty for the concentration value of each sample and correlate device specific quantities with the growth control parameters.