Preparation And Characterization Of In₂O₃Transparent Conductive Oxide Films

Transparent conducting oxide film （TCO） is a kind of important optoelectronicmaterials. Its good combination of high electrical conductivity andexcellent optical transparency in visible region makes TCO a broadapplication in optoelectronic field. Among the various TCOs, In₂O₃-based fims have thewidest use, and Tungsten-doped In₂O₃films are demonstrated as a promising TCO recently.However, previous research is focused on the growth method and photoelectric propertiesof IWO films, and few reports gave basic analysis of physical properties in IWO films.Thus, we deposit series of IWO films by radio-frequency sputtering to investigate theirstructural, elements, morphology, electrical transport and optical properties. In this thesis,the main contents are as follows:1. Three groups of IWO films were fabricated by radio-frequency magnetronsputtering technology. The square resistance of IWO films was tested by four probemethod. The electronic characterizations are affected by the varieties of sputtering time andpower. Scanning electron microscopy （SEM）, electron diffraction, X-ray diffraction （XRD）,etc. were used to characterize the In₂O₃：W（IWO） films’morphology and nanostructures.Hall Effect Measurement System was used to test electrical resistivity, carrierconcentration, and migration rate to produce tendency chart. The transmittance wasmeasured by spectrophotometer JASCO V570and the curves were studied. The opticalcharacteristic affected by the varieties of sputtering time and power.2. The first group was made under the sputtering power of100W，and the grow timewas changed to get different thickness films. The square resistance decreased when thesputtering time increased. The minimum square resistance was3.85/□when sputtering50minutues was used. The perfect crystal structure was observed from the photos of100W,50minutes In₂O₃：W（IWO） films. It was proved by the electron diffraction that theelements in the In₂O₃：W（IWO） films were In, O, and W. And the XRD profiles arematched up with the characteristic spectrum of In₂O₃. In conclusion, the W elementsubstitutes the In element in the In₂O₃：W（IWO） films. The grain size was increased firstand then decreased with time. The electrical resistivity reduced quickly, the carrierconcentration and the migration increased with sputtering time. The best transmittance average value, nearly60%, was obtained when30minutes was used. The optical band gapwas increased first and then decreased with time. Sputtering time20min got a biggeroptical band gap,3.86eV. This group obtained the minimum electrical resistivity was4.22×10-4Ω·cm, the maximum carrier concentration was7.48×1020cm-3, and the largestmigration rate was37cm2V-1s-1, respectively。3. The second group was made by different power and constant time30min, to seekfor the photoelectric properties tendency caused by power increase. The square resistancewas taken on a decrease trend when the power was strengthened. The minimum squareresistance was3.55Ω/□. The electrical resistivity reduced quickly, the carrier concentrationand the migration increased with sputtering power and decreased until125W. This groupobtained the minimum electrical resistivity was5.5×10-4·cm, the maximum carrierconcentration was8×1020cm-3, and the largest migration rate was14cm2V-1s-1,respectively。4. The third one was obtained under various sputtering power and grow time for samethickness. The square resistance decreased quickly and then slowly. The minimum squareresistance was4.57Ω/□. The perfect crystal structure was observed from the photos of100W,50minutes and150W,15minutes In₂O₃：W（IWO） films. It was proved by theelectron diffraction that the elements in the In₂O₃：W（IWO） films were In, O, and W. Andthe XRD profiles are matched up with the characteristic spectrum of In₂O₃. In conclusion,the W element substitutes the In element in the In₂O₃：W（IWO） films. The grain size wasdecreased first and then increased with the power and time variation. And sent up thesputtering power with reduced time, the electrical resistivity was decreased-increased-decreased, the migration rate was on the contrary, and the carrier concentrationwas increased. The higher transmittance average value80%and70%were get when theparameters25W,60minutes and150W,15minutes were selected. The optical band gap wasdecreased first and then increased decreased with power addition. Using150W puttering15min got a bigger optical band gap,3.98eV. This group obtained the minimum electricalresistivity was4.2×10-4Ω·cm, the maximum carrier concentration was15.2×1020cm-3, andthe largest migration rate was37cm2V-1s-1, respectively。...