Heavily doped zinc oxide with plasma frequencies in the telecommunication wavelength range

TL;DR

This paper reports a method to heavily dope zinc oxide with gallium using ion implantation and laser annealing, achieving plasma frequencies in the telecommunication wavelength range for plasmonic applications.

Contribution

The study introduces a novel doping technique combining ion implantation and laser annealing to tune ZnO's plasma frequency into the telecommunication spectrum.

Findings

Achieved free-carrier concentration of ~10^21 cm^(-3) in ZnO:Ga.

Controlled plasma wavelength down to 1.02 μm, within telecommunication range.

Demonstrated potential for ZnO as a plasmonic material in telecom applications.

Abstract

We demonstrate heavy and hyper doping of ZnO by a combination of gallium (Ga) ion implantation using a focused ion beam (FIB) system and post-implantation laser annealing. Ion implantation allows for the incorporation of impurities with nearly arbitrary concentrations, and the laser-annealing process enables dopant activation close to or beyond the solid-solubility limit of Ga in ZnO. We achieved heavily doped ZnO:Ga with free-carrier concentrations of ~10^21 cm^(-3), resulting in a plasma wavelength of 1.02 um, which is substantially shorter than the telecommunication wavelength of 1.55 um. Thus, our approach enables the control of the plasma frequency of ZnO from the far infrared down to 1.02 um, providing a promising plasmonic material for applications in this regime.