Key Sputtering Parameters for Precursor InO Films to Achieve High Carrier Mobility.

Owing to their extremely high carrier mobility (μ) of >100 cm/(V s) and suitable low carrier concentrations, transparent conducting films of solid-phase crystallized H-doped InO (spc-IO:H) exhibit high conductivity with high optical transparency over a broad frequency range. These properties can be attributed to solid-phase crystallization of the amorphous precursor film. Therefore, the development of high-quality spc-IO:H films requires the deposition conditions of the precursor films to be optimized. This study systematically investigates the effects of three key sputtering parameters, namely, water vapor partial pressure (), radio frequency magnetron sputtering power (), and flow ratio of O to total sputter gas (O) on the crystallographic texture evolution of spc-IO:H films during solid-phase crystallization. In addition, the carrier transport in the resulting films is examined. , , and O are found to be indispensable for producing high-mobility (>100 cm/(V s)) spc-IO:H films. Furthermore, it is found that introducing a small amount of during deposition, a lower , and a suitable O facilitates the formation of precursor films having a lower crystallite density. Moreover, after annealing at a temperature of 200 °C, the IO:H precursor films with a lower crystallite density are found to have larger crystal grains. However, the μ values of the postannealed IO:H films are mainly correlated with the stoichiometric deviation.