Infrared Surface Plasmon Resonances Due to Er-V Semimetallic Nanoparticles in III-V Semiconductor Matrices

Absorption resonances attributed to surface plasmons are observed in various Er-V nanoparticle/III-V semiconductor superlattices grown by molecular beam epitaxy. ErAs particles in GaAs and Ga As0.5 Sb0.5 as well as ErSb particles in GaSb and Ga As0.5 Sb0.5 are investigated. Transmission measurements indicate resonant absorption peaks from 1.2 to 2.4 μm depending on growth conditions for ErAs particles in GaAs. In the case of ErSb particles in GaSb these features are observed from about 2.4 to 4.5 μm. For the ErAs or ErSb particles grown in Ga As0.5 Sb0.5 the resonances were found to straddle the band gap of the semiconductor matrix around 1.5 μm. Growth conditions are used to engineer the nanoparticles' shape and density in order to tune the wavelength and intensity of the resonance. The asymmetry of the ErSb particles, which preferentially elongate along the [0 1- 1] direction, leads to a dependence of the resonance on polarization of the incident light. The absorption peak for light polarized parallel to the long axis of the particles is found to occur at longer wavelengths than those for that for light polarized perpendicular to the long axis of the particles.