The effects of RF power on the optical and electrical properties of transparent conductive Hf-doped In2O3 thin films

Highly transparent conductivity Hf-doped In2O3 (IHFO) films were prepared by RF sputtering on the glass substrate. The effects of sputtering power on the properties of transparent conductive films were studied to optimize the sputtering conditions. X-ray photoelectronic spectra (XPS) showed that the area ratio of OⅠ (oxygen vacancies) to OⅡ (lattice oxygen) achieved the highest value (0.71) at 75 W, resulting in IHFO having the lowest resistivity (2.76 × 10−4 Ω cm). However, the film prepared at 75 W has a low transmittance originating from the intense reflection caused by the high carrier concentration. In comparison, IHFO film deposited at 65 W has a lower resistivity and higher transmittance. Therefore, the IHFO film at 65 W exhibits the maximum figure of merit (FOM) value (7.04 × 10−2 Ω−1) with a low sheet resistance (4.03 Ω/sq) and a favorable average transmittance (88.16%). The p-CuI/n-IHFO diode is exhibited with high transmittance (84.25%) in the visible region and low guiding voltage (0.89 V), implying that IHFO films can be favorably used in the optoelectronic field.