Highly doped InP as a low loss plasmonic material for mid-IR region

Area of Science:

• Materials Science
• Optoelectronics
• Solid State Physics

Background:

• Indium Phosphide (InP) is a semiconductor material with tunable electronic properties.
• Plasmonic materials are crucial for manipulating light at the nanoscale, particularly in the mid-infrared (IR) spectrum.
• Achieving high free electron concentrations in InP is key to unlocking its plasmonic potential.

Purpose of the Study:

• To investigate the plasmonic properties of highly silicon-doped Indium Phosphide (InP) in the mid-infrared (IR) range.
• To determine the permittivity of the doped InP material.
• To simulate and experimentally verify the propagation of surface plasmon polaritons (SPPs) on InP surfaces.

Main Methods:

• Metal-organic vapor phase epitaxy (MOVPE) was used to grow highly silicon-doped InP.
• Infrared reflectance spectra were measured and fitted to determine the material's permittivity.
• Surface plasmon polaritons (SPPs) were simulated and excited using prism coupling with a high-index Germanium (Ge) prism.
• Diffraction patterns were analyzed on periodically structured InP surfaces.

Main Results:

• The permittivity of the highly doped InP was successfully retrieved.
• Simulations of SPP propagation showed good agreement with experimental results.
• Excitation of SPPs led to diffraction into symmetry-prohibited orders on structured surfaces.
• Highly doped InP demonstrated effective plasmonic behavior in the mid-IR.

Conclusions:

• Highly doped InP is confirmed as an effective plasmonic material for mid-IR applications.
• The study validates theoretical models of SPP propagation in doped InP.
• Experimental observation of unique diffraction phenomena highlights the material's potential for novel optical devices.