In view of the great demand for large-area silicon detectors in domestic nuclear physics experiments, a type of 300-μm-thick high-performance square silicon detector with a large active area of 50 mm×50 mm by using overprinting technology is developed in the Institute of Modern Physics of the Chinese Academy of Sciences. Based on this technology, SiO ₂contamination caused by the photolithography and corrosion processes is effectively reduced. The detector has an excellent performance with a yield of up to 80%. Under –45 V (depletion voltage) bias, the leakage current of the detector is less than 40 nA. The detector is tested with a three-component α radioactive source. The energy resolution ( σ) is about 45 keV for 5-MeV α particles. Used as an energy deposition(Δ E) detector, the detector performance is also tested for measuring reaction products of 250 MeV/u ¹¹C radioactive beams impinging on a carbon target. The results show that the charge number resolution of a single silicon detector is 0.17 for the carbon isotope, which is similar to that measured with the same type of detectors available from the market. With the average deposition energy of three silicon detectors used, the charge number resolution for carbon isotope reaches a better value of 0.11. With this resolution, C and B isotopes are clearly distinguished, meeting the requirements for particle identification in intermediate- and high-energy radioactive beam experiments.