As a new common material fabrication technique, Ge/Si heterogeneous wafer bonding exhibits enormous potentials in the fabrication of high-quality Si-based Ge films. It is also regarded as an alternative solution for the fabrication of high-performance Ge/Si photoelectric devices. However, there easily exists a nanometer GeO₂ oxide layer at the Ge/Si bonded interface fabricated by the direct bonding or plasma bonding method. This leads to the formation of an interface state at the Ge/GeO₂ and GeO₂/Si semiconductor-insulator contact layer, which in turn affects the performance of the device. A low-temperature Ge/Si bonded interface is constructed based on the three carrier transport equations, the non-local tunneling model, and the semi-classical quantum solution. The effect of the interface state density (ISD) on the carrier electrical transport, light absorption, recombination, and high-frequency response is studied. The results show that with the increase of ISD, the dark current of the Ge/Si heterojunction increases. At the same time, the carrier capture effect becomes more obvious, leading to the decrease in the total current and the spectral response. In addition, the increase of ISD leads to the worsening frequency response and the decrease in the electric field within the Ge layer. Moreover, the ISD must be smaller than 1×10 ¹² cm ^-2 to obtain a high-performance Ge/Si bonded heterojunction. These results may give a theoretical guidance for the fabrication of high-quality Si-based Ge films and high-performance Ge/Si photoelectric devices.