High infrared responsivity of silicon photodetector with titanium-hyperdoping

Silicon (Si) photodetectors have advantages of low cost, convenient preparation, and high integration. However, limited by the indirect bandgap of 1.12 eV, Si photodetectors cannot perform at the wavelength beyond 1100 nm. It is attractive to extend the response wavelength of Si-based photodetectors for the optoelectronics application in recent years. In this article, we have successfully prepared a high-performance photoconductive detector based on titanium-hyperdoped Si (Si:Ti). The Si:Ti material shows an enhanced infrared absorption primarily attributed to the sub-bandgap photo excitation assisted by titanium (Ti)-induced energy states with an average energy level of E-v + 0.23 eV. Moreover, the detector exhibits a high responsivity of 200 mA W-1 under 1550 nm light at 5 V bias, which is higher than previously reported transition metals hyperdoped silicon detectors. These results are helpful for the development of infrared hyperdoped silicon photodetectors in the field of optoelectronics.