Controllable Modulation of Surface Plasmon Resonance Wavelength of ITO Thin Films

The tin-doped indium oxide (ITO) thin films arc fabricated on the float glass substrates by the direct current (DC) magnetron sputtering method. The ITO thin films with different thicknesses arc fabricated by changing the deposition time. As the film thickness gradually increases from 16 nm to 271 nm, the crystallinity is enhanced and the corresponding carrier concentration is increased from 4.79 X 10(20) cm(-3) to 2.41 X 10(21) cm(-3). Thus the corresponding surface plasmon resonance (SPR) wavelength blueshifts from 1802 nm to 1204 nm. The controllable modulation of near infrared SPR wavelength within a relatively broad range is realized. The SPR wavelength of the ITO films with different film thicknesses arc theoretically calculated by using the Drude free electron gas model, which further confirms that the effective modulation of SPR wavelength is determined by the influence of film thickness on carrier concentration.