Extended-SWIR Photodetection in All-Group IV Core/Shell Nanowires

TL;DR

This paper demonstrates the development of Ge/GeSn core-shell nanowire photodetectors that operate efficiently in the short-wave infrared range at room temperature, leveraging tunable bandgap and enhanced lattice strain relaxation.

Contribution

It introduces all-group IV core-shell nanowire heterostructures with uniform composition and high crystallinity for broadband infrared photodetection, a novel approach in silicon-compatible nanophotonics.

Findings

Achieved high responsivity of 2.7 A/W at 1550 nm.

Extended cutoff wavelength to 2.1 μm.

Demonstrated superior optoelectronic properties in nanowire transistors.

Abstract

Group IV Ge1-xSnx semiconductors hold the premise of enabling broadband silicon-integrated infrared optoelectronics due to their tunable bandgap energy and directness. Herein, we exploit these attributes along with the enhanced lattice strain relaxation in Ge/Ge0.92Sn0.08 core-shell nanowire heterostructures to implement highly responsive, room-temperature short-wave infrared nanoscale photodetectors. Atomic-level studies confirm the uniform shell composition and its higher crystallinity with respect to thin films counterparts. The demonstrated Ge/Ge0.92Sn0.08 p-type field-effect nanowire transistors exhibit superior optoelectronic properties achieving simultaneously a relatively high mobility, a high ON/OFF ratio, and a high responsivity, in addition to a broadband absorption in the short-wave infrared range. Indeed, the reduced bandgap of the Ge0.92Sn0.08 shell yields an extended cutoff wavelength of 2.1 um, with a room-temperature responsivity reaching 2.7 A/W at 1550 nm. These results highlight the potential of Ge/Ge1-xSnx core/shell nanowires as silicon-compatible building blocks for nanoscale integrated infrared photonics.