Extended X-ray absorption fine structure of InAsPSb

InAsPSb is a quaternary of great importance because it can be lattice-matched to InAs and with an energy gap covering mid-infrared spectral range. This alloy, however, suffers from immiscibility problems when its As composition is lower than 0.4. According to the valence force field (VFF) model, bond lengths in an alloy resemble those in corresponding end-point binaries. Because of the large difference between the In-P and In-Sb bond length, the concomitant incorporation of P and Sb in InAsPSb could be energetically unfavourable, leading to phase separation during the growth. For the time being, short range atomic arrangement in this alloy is still lack of study. In this work, we use extended X-ray absorption fine structure (EXAFS) to study the bond lengths and short range structures in InAsPSb alloys with different compositions.