Hyperdoped Crystalline Silicon for Infrared Photodetectors by Pulsed Laser Melting: A Review

Infrared photodetectors based on crystalline silicon have attracted much attention due to their low cost and good compatibility with complementary metal–oxide–semiconductor (CMOS) technology in ultra-largescale integrated circuits (ULSI). However, silicon shows no response to infrared light with a wavelength of over 1100 nm corresponding to its bandgap of 1.12 eV. Pulsed laser melting and rapid solidification are effective ways to hyperdope high concentrations of deep-level impurities into silicon, and therefore form an impurity band within the bandgap, allowing broad-band infrared light to be absorbed. Herein, a review of the fundamentals and research progress of hyperdoped silicon and related infrared photodetectors during the past few decades is given. The fundamentals of hyperdoped silicon, including the hyperdoping mechanism and infrared light absorption or response, are first discussed. Then, the fabrication methodologies and properties of hyperdoped silicon with various elementals (chalcogens and transition metals) are illustrated, among which the corresponding photodetectors’ properties are stressed. Earlier research on chalcogen hyperdoping paves the path for silicon to be used for infrared photodetectors and later research on transition metals hyperdoping provides a new opportunity for further improvements of device properties. Finally, a summary and future research direction of hyperdoped silicon are outlined.