# Optical Properties of GePb Alloy Realized by Ion Beam Technology

## TL;DR

Researchers used ion beam technology to create GePb alloys with optical properties suitable for short-wave infrared applications.

## Contribution

A CMOS-compatible method for fabricates nanostructured GePb alloys with tunable optical properties for SWIR applications.

## Key findings

- GePb alloys exhibit a reduced bandgap compared to pure Ge, enabling longer-wavelength emission.
- Nanostructured GePb surfaces provide broadband antireflective properties below 1800 nm wavelengths.
- The fabrication process is compatible with CMOS technology, enabling integration into existing semiconductor processes.

## Abstract

Incorporating lead (Pb) into the germanium (Ge) lattice emerges as a promising approach for bandgap engineering, enabling luminescence at longer wavelengths and paving the way for enhanced applications in short-wave infrared (SWIR) light sources and photodetectors. In this work, we report on optical properties of GePb alloys fabricated by a complementary metal-oxide semiconductor (CMOS)-compatible process that includes Pb ion implantation followed by solid-phase epitaxial regrowth via flash-lamp annealing. Optical characterization, including photoluminescence spectroscopy and Fourier-transform infrared reflectance spectroscopy, reveals that GePb alloys exhibit a reduced bandgap compared to pure Ge, resulting in longer-wavelength emission, while also providing broadband antireflective properties below 1800 nm wavelengths due to the surface subwavelength nanostructure. These findings position nanostructured GePb as a highly promising candidate for SWIR optoelectronic applications.