Development of ZnO films for near-IR plasmonics

摘要

Ga-doped ZnO grown at 200 ℃ by pulsed-laser deposition in Ar ambient and annealed face-down on Zn foil at 500 ℃ in forming gas can attain near-record electrical characteristics for ZnO: resistivity p = 1.23 × 10~(-4) Ω-cm, mobility μ_(Hall) = 34.1 cm~2/V-s, and free-electron concentration n = 1.4 × 10~(21) cm~(-3) , leading to a plasmonic resonance wavelength λ_(res) = 1.05 μm. A value of λ_(res) near 1 μm is important because metal-based plasmonics are lossy in the IR region. Longer resonant wavelengths in ZnO, e.g., the telecommunication wavelengths λ_(res) =1.3 and 1.55 μm, are then simply produced by furnace anneals in air. A relatively unexploited characterization tool for such materials is spectroscopic ellipsometry (SE). By harnessing the full potential of SE we demonstrate full-color maps of thickness d, concentration n_(SE), and mobility μ_(SE).