Extended room-temperature infrared photoresponse in hyperdoped Si by ion implantation

Presently, silicon photonics requires photodetectors that are sensitive in a broad infrared range, can operate at room temperature, and are suitable for integration with the existing Si technology process. Here, we demonstrate strong room-temperature sub-bandgap photoresponse of photodiodes based on Si hyperdoped with chacolgen ions. The epitaxially recrystallized hyperdoped Si layers are developed by ion implantation combined with pulsed laser melting and incorporate Se/Te dopant concentrations several orders of magnitude above the solid solubility limit. With increasing the impurity concentration, the hyperdoped Si is changed from insulating to quasi-metallic with a finite conductivity as the temperature tends to zero. The optical absorptance is found to increase monotonically with increasing dopant concentration and extends well into the mid-infrared range. Temperature-dependent optoelectronic photoresponse unambiguously demonstrates that the extended infrared photoresponsivity from hyperdoped Si p-n photodiodes is mediated by an impurity band within the upper half of the Si bandgap. This work contributes to pave the way towards establishing a Si-based broadband infrared photonic system operating at room temperature.
References: Sci. Reports 7, 43688 (2017), Phys. Rev. Appl. 10, 024054 (2018) and Adv. Mater. Inter. 5, 1800101 (2018), Phys. Rev. Applied 11, 054039 (2019).