Despite the large lattice mismatch of 7.2% with respect to GaAs, the InAs photoconductor has been successfully fabricated on the GaAs substrate by molecular-beam epitaxy. Both the responsivity and the detectivity of the detector depend on the bias voltage across the device. When tested under an 800 K blackbody source, the highest achieved responsivity at 77 K is 34.5 A/W. The maximum specific detectivity is 1.3 x 10(11) cm Hz(1/2)/W at 77 K. At 300 K, the highest responsivity and detectivity are 0.7 A/W and 2.1 x 10(8) cm Hz(1/2)/W, respectively.