Reflectance anisotropy spectroscopy of strain-engineered GaAsBi alloys

In this paper, we present results obtained by an optical technique, namely, reflectance anisotropy spectroscopy (RAS), applied to a series of GaAs1−xBix samples grown molecular beam epitaxy (MBE) under different strain conditions with the increasing concentration Bi, up higher value about 7%. The epitaxial buffer layers for growing layer were prepared either compressive (as it is commonly done) or tensile strain: latter case has been proven be strategy that allows us obtain better crystalline quality [Tisbi et al., Phys. Rev. Appl. 14, 014028 (2020)]. A characteristic, well defined signal below 2.5 eV demonstrated connected presence Bi and, in particular, produced sub-surface region voluminous atoms. amplitude directly relates quantity, while its sign gives information local clustering/ordering atoms sample. We conclude detailed interpretation RAS signatures and knowledge their origin offer opportunity utilize technique follow real time GaAsBi growth MBE metal organic vapor phase processes.