Effect of interface composition on the band offsets at InAs/AlSb (001) heterojunctions

X‐ray photoemission spectroscopy has been used to directly measure the dependence of the valence band offset ΔEv on interface composition (AlAs‐like versus InSb‐like) for InAs/AlSb (001) heterojunctions grown by molecular‐beam epitaxy. A staggered band alignment with a consistent average value of ΔEv = 0.16 eV is measured for three samples with the InSb‐like interface. A difference of 0.07 eV is observed between the average ΔEv values for two AlAs‐like interface samples (0.15 and 0.22 eV, respectively). The growth‐to‐growth variation in ΔEv value for the AlAs‐like interface, and the 0.06 eV difference between the InSb‐like ΔEv value and the larger AlAs‐like ΔEv value are both attributed to interface composition differences. We interpret the ΔEv = 0.22 eV value as being most characteristic of the AlAs‐like interface. A tight binding model calculation of the effect of local strain on InAs/AlSb band offsets is compared to experiment.