Extended infrared photoresponse in room-temperature Si hyperdoped with Te

Presently, room-temperature infrared sub-band-gap photoresponse in Si is of great interest for the development of on-chip complementary-metal-oxide-semiconductor (CMOS)-compatible photonic platforms [1]. One of the most promising approaches to further extend the photoresponse of Si to the mid- and far-infrared (MIR/FIR) ranges consists of introducing deep-level dopants into the Si band gap at concentrations in excess of the solid solubility limit [2]. In this work, we demonstrate strong room-temperature sub-band-gap photoresponse of photodiodes based on Si hyperdoped with tellurium [3]. A CMOS-compatible approach of combining ion implantation with pulsed laser melting was applied to synthesize single-crystalline and epitaxial Te-hyperdoped Si layers with a Te concentration five orders of magnitude above the solid solubility limit. Driven by increasing Te concentration, both the insulator-to-metal transition and a band-gap renormalization are observed. The sub-band optical absorptance in the resulting Te-hyperdoped Si layers is found to increase monotonically with increasing Te concentration and extends well into the MIR/FIR ranges (1.4 to 25 μm). Importantly, the MIR/FIR optoelectronic response from Te-hyperdoped Si photodiodes is demonstrated to be related with known Te deep-energy levels into the Si band-gap. This work contributes to pave the way towards establishing a Si-based broadband infrared photonic system operating at room temperature.