Near-infrared (1 to 4 μ m ) control of plasmonic resonance wavelength in Ga-doped ZnO

Abstract

The plasmonic resonance wavelength λres in ZnO doped with 3 wt.% Ga2O3 can be controlled over the range 1 to 4 μm by simple furnace annealing in flowing Ar. For each annealing temperature TA, the reflectance Rm and transmittance Tm are measured over a wavelength range, λ=185 to 3200 nm, (energy range, E=6.7 to 0.387 eV), and the reflectance coefficient R is calculated from Rm and Tm. The value of λres is then determined from a Drude-theory analysis of R versus E that yields fitting parameters nopt (optical carrier concentration), μopt (optical mobility), high-frequency dielectric constant ϵ∞, and thickness d at each annealing temperature TA. The validity of this process is confirmed by comparison of ϵ∞ with literature values and comparison of nopt and μopt with analogous quantities n and μH measured by the Hall effect.