On the growth of transparent conductive oxide ternary alloys Zn-Ir-O (ZIRO) by the means of rf magnetron co-sputtering

We report here on an alternative approach for forming p-type transparent conductive oxide ternary alloys Zn-Ir-O (ZIRO) by the means of rf magnetron co-sputtering of Ir and zinc nitride targets in a mixed argon and oxygen plasma. The structural and optical properties of ZIRO thin films formed on both glass and Si (100) substrates have been studied by Energy Dispersive X-ray spectrometry (EDX), X-Ray Diffraction (XRD), Raman and optical spectrophotometry. The EDX results outlined that the Ir incorporation in ZIRO alloys saturates at 3.3% when the rf co-sputtering is done in a plasma containing above 2% O2. XRD and Raman spectroscopy analysis revealed that all films were polycrystalline containing only the ZnO and IrO2 phases. The presence of Ir in ZIRO thin films does affect their optical transparency below 500 nm while it remains comparable to that of ZnO above 500 nm down to the infrared spectral range. Moreover the physical properties of the ZIRO films have been studied after sequentially annealing in air or forming gas (95% N2-5% H2) at elevated temperatures up to 700 °C. All ZIRO films were found to remain highly resistive (MΩ range) regardless of annealing treatment conditions. The optical transparency of these films was found to be further reduced upon annealing at temperatures above 500 °C.