Influence of RF Sputtering Pressure and Power on the Microstructure of Sb Thin Films

Antimony (Sb) thin films are critical precursors for next-generation chalcogenide-based optoelectronics. However, the synergistic effects of sputtering power and pressure on their growth dynamics are not yet fully understood. The objective of this study is to establish the conditions for controlling the growth process of Sb films. To this end, we systematically investigated the interplay between RF-Sputtering parameters and film functionality. Samples were deposited as ~800 nm-thick films using RF-Sputtering, varying the power (50-70 W) and working pressure (10-25 mTorr), followed by comprehensive structural (XRD), morphological (SEM), chemical (XPS), and electrical characterization. A critical power threshold of 60 W was identified for the amorphous-to-crystalline transition, at which the films adopt a rhombohedral phase. Increasing the power to 70 W triggered a significant texture redistribution toward the (104) plane and an increase in grain size from 40 nm to 110 nm. Consequently, electrical resistivity dropped by several orders of magnitude, reaching a minimum of ~10^-4 Ω cm due to enhanced grain connectivity and reduced boundary scattering and the transition from semiconductor-type conductivity to metallic-type conductivity. XPS analysis confirmed that these variations are driven by microstructural evolution rather than chemical changes, as the films maintain a stable metallic character beneath a nanometric surface oxide. These findings establish a direct correlation between plasma conditions and material properties. This strategic framework supports the optimization of Sb-based precursor layers in high-efficiency thin-film technologies.