Broadband photoresponse enhancement by band engineering in Sb-doped MnBi2Te4

TL;DR

This paper demonstrates that Sb doping in MnBi2Te4 reduces carrier concentration and enhances broadband photoresponse, especially in the infrared, by suppressing recombination and improving photodetector performance.

Contribution

It introduces band engineering via Sb doping in MnBi2Te4 as a novel method to significantly improve infrared photoresponsivity and response times in topological material-based photodetectors.

Findings

Responsivity at 1550 nm reaches 3.02 mA/W with 18.5 μs response time.

Responsivity at 4 μm reaches 0.795 mA/W with 9.0 μs response time.

Nearly two orders of magnitude improvement over undoped MnBi2Te4.

Abstract

Topological materials have attracted considerable attention for their potential in broadband and fast photoresponse, particularly in the infrared regime. However, the high carrier concentration in these systems often leads to rapid recombination of photogenerated carriers, limiting the photoresponsivity. Here, we demonstrate that Sb doping in MnBi2Te4 effectively reduces carrier concentration and suppresses electron-hole recombination, thereby significantly improving the optoelectronic performance across the visible to mid-infrared spectra. The optimally doped Mn(Bi0.82Sb0.18)2Te4 photodetector achieves a responsivity of 3.02 mA W-1 with a response time of 18.5 {\mu}s at 1550 nm, and 0.795 mA W-1 with a response time of 9.0 {\mu}s at 4 {\mu}m. These values represent nearly two orders of magnitude improvement compared to undoped MnBi2Te4. Our results highlight band engineering as an effective strategy to enhance the infrared performance of topological material-based photodetectors, opening new avenues for high-sensitivity infrared detection.