Near infrared light detection is fundamental for sensing in various application fields. In this paper, we detail the properties of InGaAs/AlGaAs multiple quantum well (MQW) photodetectors (PDs) monolithically integrated by direct epitaxy on 300 mm Si(001) substrates. A MQW high crystalline quality is achieved using 300 mm Ge/Si pseudo-substrates with a low threading dislocation density of 4 × 107 cm−2 from electron channeling contrast imaging measurements. The localized states in the MQW stack are investigated using temperature-dependent photoluminescence. Two non-radiative recombination channels are identified. The first one is due to delocalized excitons generated by potential’s fluctuations because of the InGaAs/AlGaAs interfacial roughness (with an activation energy below 4 meV). The second one is due to exciton quenching because of the presence of numerous threading dislocations. A low dark current density of 2.5 × 10−5 A/cm2 is measured for PDs on Ge/Si substrates, i.e., a value very close to that of the same PDs grown directly on GaAs(001) substrates. A responsivity of 36 mA/W is otherwise measured for the photodiode on Ge/Si at room temperature and at −2 V.
