| Gallium doped ZnO transparent conductive oxide thin films have been widely used in optoelectronic devices such as low-E glass,thin film solar cell and smart window due to their excellent optical and electrical properties,low-cost and sufficient supply of raw materials.Meanwhile,GZO is a new type of near-infrared plasmonic metamaterials,which is expected to replace conventional metal metamaterials used in near-infrared photoelectric devices.This dissertation will present the following four parts:?1?Tailoring the carrier concentration of GZO thin films by Zn vacancy;?2?Preparing high conductive GZO thin films on flexible substrates;?3?Tailoring the haze of GZO thin films on flexible substrates;?4?Tailoring the plasmonic resonance wavelength of GZO thin films.The major findings are listed as follows:1.Highly transparent conductive Zn/GZO ultrathin films were prepared by magnetron sputtering at RT combined with a post-RTA treatment,and the effects of Zn thickness on the structural,optical,and electrical properties of the resulting films were investigated.It was shown that increasing the Zn thickness improved the carrier concentration and mobility.By optimizing the thickness of the Zn layer between GZO and glass,we obtain GZO films with a low resistivity of 4 × 10-4 ?·cm,a carrier concentration of 1 ×1021 cm-3 and a mobility of 15.3 cm-2V-1s-1.In addition,the annealed Zn/GZO thin films are found to be highly transparent with an average transmittance over 84% in the visible range.The above results show that the thermal diffusion of Zn atom effectively filled the Zn vacancy and improved the carrier concentration in GZO thin film.Moreover,reducing Zn vacancy improved the mobility of GZO thin films.2.Highly transparent and conductive HGZO thin films were successfully deposited on PET substrates by RF magnetron sputtering of a ceramic target at room temperature.The effects of RF power and Ar + H2 flow rate on electrical,optical and structural properties of HGZO thin films were investigated systematically.It was revealed that HGZO thin film with a resistivity of 7.1 ×10-4 ?·cm and an average transmittance of 77.3% at 400-800 nm was obtained at the optimized process parameters?RF power: 120 W and Ar + H2: 20 sccm?.The corresponding carrier concentration and mobility were respectively 7.1 ×1020 cm-3 and 12.4 cm-2V-1s-1.The figure of merit as defined by Haacke was up to 2.9 ×10-3 ?-1.Furthermore,the maximum specular transmittance of HGZO-PDLC device was 66.3% at the driving voltage of 60 V.3.High haze GZO thin films were prepared on flexible substrates by RF magnetron sputtering deposition at room temperature.Utilizing the natural texture of PEF substrate,GZO/PEF films with a haze value of 67.7% at 550 nm without sacrificing the transmission in the visible band were obtain by one-step method.The corresponding sheet resistance was 29.3 ?/sq.By utilizing the mie scattering of SiO2 spheres in PI substrate,a flattened light-scattering GZO flexible conductive electrode was successfully prepared.The GZO/PI?SiO2?electrode had an average scattering of 40.7% in the 400-800 nm.The roughness was only 7.59 nm,which was attributed to the liquid of PI.4.The effects of Ga2O3 content in the target and substrate temperature on the electrical,structural and optical properties of GZO films deposited on glass substrates by RF magnetron sputtering were investigated.It is found that the film deposited at optimized conditions?Ga2O3 content = 5 wt%,substrate temperature = RT?had the highest carrier concentration of 7.0 × 1020 cm-3.Correspondingly,the real part of the permittivity of the GZO film is negative at 1.55 ?m.Absorption losses in these GZO films are less 10 times smaller than those observed in conventional Ag films at the telecommunication wavelengths of 1.55 ?m.In addition,the values of plasmonic resonance wavelength can be changed from1.35 to 2.39 ?m.These results showed that GZO film was a promising low-loss alternative material to conventional metals for plasmonic application at near infrared band.Based on aboved results,we have designed,fabricated and characterized a broadband and wide-angle thin-film perfect absorber in the near infrared range by preparing a SiO2/bi-layer GZO/Ag thin-film structure on the glass substrate.The thin-film absorber demonstrates a broadband PA from 1.24 ?m to 1.49 ?m.Moreover,the optical properties of the thin-film absorber are robust with angles of incidence from 0° to 60°. |
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