Electrical and structural study on indium zinc oxide thin films by sputtering process

One disadvantage of currently available indium-zinc oxides (IZOs) is the high content of indium. This high composition of In is costly and difficult for massive production, which is crucially required for solar energy and display applications. IZOs already demonstrated higher optical transmittance (> 75%) than that of aluminum zinc oxides (AZO); better resistance to water vapor than zinc oxides (ZnO); and relatively good electrical conductivity. Therefore, improvements of IZOs could be worthy of attention. In this study, relatively low indium IZO thin films were deposited on glass substrates using magnetron sputtering with a mixed 53 wt.% In2O3 + 47 wt.% ZnO target. To monitor the process, both Langmuir probe and optical emission spectrometer were employed to investigate the plasma conditions. Several parameters such as plasma potential, electron and ion densities were carefully recorded and analyzed. On the other hand, the structure and electrical resistivity of films were examined by XRD and four-point probe. The correlations between the process parameters (Ar flow rate) and films' properties were assessed based upon results from the plasma diagnostics.

► Low In IZO films were deposited by sputtering under different Ar flow rates.
► The target is mixed 53 wt.% In2O3 and 47 wt.% ZnO.
► Langmuir probe and OES were used for plasma diagnostics.
► Higher Ar flow rate enhanced plasma potential, ion/electron densities.
► Nanocrystalline In2O3 with a compound phase Zn2In2O5 in the films was identified.