Optical (a) transmission, (b) reflectance, and (c) absorbance spectra and (d) I-V plots of In2O3 NPs and nanostructured In2O3 films. The optical absorption
properties of the In2O3 NPs and the nanostructured In2O3 films were further analyzed according to their absorbance (A) spectra as shown in Figure 4c. Two spectral regions can be recognized from the A spectra. At the visible region (λ > 350 nm), the A of the In2O3 NPs was greater than that of the nanostructured In2O3 films due to the larger surface-to-volume ratio of the NPs, which was previously discussed. Conversely, the A of the nanostructured In2O3 films was about one time greater than that of the In2O3 NPs at the UV region (λ < 350 nm), where the incident photon energy was greater than the E opt of
In2O3. The photon absorption at the high-energy (>E opt) region is attributed to the direct transition of In2O3. The nanostructured In2O3 films formed after the buy eFT508 thermal treatment process possessed higher crystallinity and more compact structures compared to the In2O3 NPs. Thus, they can effectively absorb the incident photon during the photon interaction. I-V plots of the In2O3 NPs and nanostructured In2O3 films are shown in Figure 4d. The increase in slope for the nanostructured In2O3 films indicates an enhancement in the conductance of the In2O3. This can be explained by the improvement in the interconnection between the nanostructures of In2O3 as shown in the FESEM GS1101 images which thereby improves the charge mobility of the In2O3 structures. Moreover, the conductivity of the In2O3 nanostructures LY333531 research buy is also strongly related to surface-adsorbed oxygen molecules . Upon exposure to air, the electrons in In2O3 nanostructures will transfer to the surface of the nanostructures and ionize the oxygen source from the air to form an oxygen surface layer. This process creates an electron depletion layer, thus reducing the conductivity of the In2O3 nanostructures. The large surface-to-volume
ratio of the untreated In2O3 NPs indicates higher resistance compared to the treated nanostructured In2O3 films due to the significant amount of oxygen molecules bonded to the surface of the NPs which generated a broader electron depletion layer. Resistivity values calculated from the I-V curves were 4.3 × 10−2 and 1.3 × 10−2 Ω cm for the In2O3 NPs and nanostructured In2O3 films, Sodium butyrate respectively. The resistivity value of the treated In2O3 nanostructures is smaller than the reported value for the undoped In2O3 films (about 5 × 10−2 Ω cm) . The characterizations above demonstrated that by changing their microstructure arrangement through the in situ thermal radiation treatment process in N2O plasma, there was an improvement in the crystallinity and optical and electrical properties of the In2O3 NPs. In order to understand the microstructure deformation process, the cross-sectional FESEM images of the untreated and thermally treated In2O3 NPs were analyzed as shown in Figure 5a.