A high detectivity multiquantum well midinfrared photodetector is reported. It is based on a strain compensated InGaAs/InGaP on InP structure, using bound-to-continuum intersubband absorption, with&lgr;P=4.9 &mgr;mand ∼0.5 &mgr;m full width at half maximum. This design is unique by enabling a large critical thickness, thus increasing the quantum efficiency. Photodetectors with background-limited performance (BLIP) with detectivity ofD&lgr;*(BLIP)=3.2×1010 cmHz/Wup to 110 K, with only ten quantum well periods were implemented. Arguments are given to predict an optimized background-limited performance for this design up to 135 K. ©1998 American Institute of Physics.