Si‐based photodetectors satisfy the criteria of being low‐cost and environmentally friendly, and can enable the development of on‐chip complementary metal‐oxide‐semiconductor (CMOS)‐compatible photonic systems. However, extending their room‐temperature photoresponse into the mid‐wavelength infrared (MWIR) regime remains challenging due to the intrinsic bandgap of Si. Here, we report on a comprehensive study of a room‐temperature MWIR photodetector based on Si hyperdoped with Te. The demonstrated MWIR p‐n photodiode exhibits a spectral photoresponse up to 5 µm and a slightly lower detector performance than the commercial devices in the wavelength range of 1.0–1.9 µm. The correlation between the background noise and the sensitivity of the Te‐hyperdoped Si photodiode, where the maximum room‐temperature specific detectivity is found to be 3.2 × 1012 cmHz1/2 W−1 and 9.2 × 108 cmHz1/2 W−1 at 1 µm and 1.55 µm, respectively, is also investigated. This work contributes to pave the way towards establishing a Si‐based broadband infrared photonic system operating at room temperature.

Room‐temperature broadband infrared photoresponse in Si is of great interest for the development of on‐chip complementary metal–oxide–semiconductor (CMOS)‐compatible photonic platforms. One effective approach to extend the room‐temperature photoresponse of Si to the mid‐infrared range is the so‐called hyperdoping. This consists of introducing deep‐level impurities into Si to form an intermediate band within its bandgap enabling a strong intermediate band–mediated infrared photoresponse. Typically, impurity concentrations in excess of the equilibrium solubility limit can be introduced into the Si host either by pulsed laser melting of Si with a gas‐phase impurity precursor, by pulsed laser mixing of a thin‐film layer of impurities atop the Si surface, or by ion implantation followed by a subsecond annealing step. In this review, a conspectus of the current status of room‐temperature infrared photoresponse in hyperdoped Si by ion implantation followed by nanosecond‐pulsed laser annealing is provided. The possibilities of achieving room‐temperature broadband infrared photoresponse in ion beam–hyperdoped Si with different deep‐level impurities are discussed in terms of material fabrication and device performance. The thermal stability of hyperdoped Si with deep‐level impurities is addressed with special emphasis on the structural and the optoelectronic material properties. The future perspectives on achieving room‐temperature Si‐based broadband infrared photodetectors are outlined.

Hyperdoped silicon with deep level impurities has attracted much research interest due to its promising optical and electrical properties. In this work, single crystalline silicon supersaturated with titanium is fabricated by ion implantation followed by both pulsed laser melting and flash lamp annealing. The decrease of sheet resistance with increasing Ti concentration is attributed to a surface morphology effect due to the formation of cellular breakdown at the surface and the percolation conduction at high Ti concentration is responsible for the metallic-like conductivity. The insulator-to-metal transition does not happen. However, the doping effect of Ti incorporation at low concentration is not excluded, which might be responsible for the sub-bandgap optical absorption reported in literature.

Hyperdoping Si with chalcogens is a topic of great interest due to the strong sub-bandgap absorption exhibited by the resulting material, which can be exploited to develop broadband room-temperature infrared photodetectors using fully Si-compatible technology. Here, we report on the critical behavior of the impurity-driven insulator-to-metal transition in Tehyperdoped Si layers fabricated via ion implantation followed by nanosecond pulsed-laser melting. Electrical transport measurements reveal an insulator-to-metal transition, which is also confirmed and understood by density functional theory calculations. We demonstrate that the metallic phase is governed by a power law dependence of the conductivity at temperatures below 25 K, whereas the conductivity in the insulating phase is well described by a variablerange hopping mechanism with a Coulomb gap at temperatures in the range of 2-50 K. These results show that the electron wave-function in the vicinity of the transition is strongly affected by the disorder and the electron-electron interaction.