p+‐InSb/&pgr;‐InAs1−xSbx/n+‐InSb heterojunction photodiodes operating at near room temperature in the 8–13 &mgr;m region of infrared (IR) spectrum are reported. A room‐temperature photovoltaic response of up to 13 &mgr;m has been observed at 300 K with anx≊0.85 sample. The voltage responsivity‐area product of 3×10−5V cm2/W has been obtained at 300 K for the &lgr;=10.6 &mgr;m optimized device. This was close to the theoretical limit set by the Auger mechanism, with a detectivity at room temperature of ≊1.5×108cm Hz1/2/W. ©1995 American Institute of Physics.