Two InAs quantum dot samples have been grown by the solid source molecular beam epitaxy (MBE) and fabricated to detectors. AlGaAs thin films have been inserted into the source region for one of the two devices. The structural features of the two samples have been studied by using the transmission electron microscope (TEM). The photoelectric properties of them have been measured by the photoluminescence (PL) and photocurrent (PC) spectra. The experimental results indicated that the AlGaAs films have profound effects on the properties of the detector. According to the calculations based on effective mass approximation, the origins of the photocurrent peaks of the two devices have been identified.