Abstract: A semiconductor device and a semiconductor die are disclosed. The semiconductor device includes: a SPAD wafer containing SPAD dies formed thereon with respective SPAD arrays; a TDC wafer containing TDC dies formed thereon with respective TDC arrays; and a logic wafer containing logic dies formed thereon with respective peripheral logic circuits. The SPAD wafer, TDC wafer and logic wafer are bonded in the sequence set forth. The TDC arrays and peripheral logic circuits are arranged on the TDC and logic wafers, respectively, and the SPAD arrays are bonded to the TDC arrays. The three wafers are bonded and integrated together to form the semiconductor device using a multi-wafer stacking technique. The increased integration of the semiconductor device means an increased fill factor of SPAD arrays for same size, resulting in improved photon detection efficiency of the semiconductor device and improved detection performance of single-photon detectors fabricated from the semiconductor device.