A high performance InGaAs/GaAs/AlGaAs superlattice-coupled quantum well infrared (IR) photodetector grown on the semi-insulating GaAs substrates by using molecular beam epitaxy has been developed for long wavelength IR detection. The dark current-voltage (I-V) and spectral responsivity characteristics were measured and analyzed on this device. The maximum measured responsivity (R i ) and the estimated peak detectivity (D * ) at λ p =10.5μm under positive bias condition were found to be 4.95 A/W and 1.83x10 1 0 cmHz 1 / 2 /W at V b =3.15 V and T=20 K, respectively.