We report on the growth and opto-electronic characterization of type-II InAs/GaSb superlattice (SL) mid-wavelength infrared pin photodetector grown on a GaAs substrate. AlSb interfacial misfit array was employed at the GaAs buffer/GaSb epilayer interface to reduce the dislocation density of the SL structure grown on the lattice mismatched GaAs substrate. Optical and electrical performance of this sample (SL-GaAs) were then compared with the reference sample of the same structure grown on a GaSb substrate (SL-GaSb). At 80 K, the dark current density and the detectivity values of the pin photodetectors were recorded as 5.40. x. 10-3 A cm-2 and 2.34. x. 1010 cm Hz0.5W(-1) for the SL-GaAs and 9.50. x. 10(-4) A cm(-2) and 4.70. x. 1010 cm Hz0.5W(-1) for the SL-GaSb, respectively.