X-ray study of tin oxide films obtained by reactive DC sputtering from a metallic tin target in pure oxygen plasma

Tin oxide films deposited on glass substrates were prepared using a metallic tin target in a DC-magnetron sputtering system. Pure oxygen (99.9%) was used as oxidant and plasma gas. The experiments were carried out at a fixed current mode of the power supply and the cathode voltage was measured during 15 min, the first 5 min of pre-sputtering and the last 10 were used for film growth. The deposition was carried out under different conditions of current, oxygen pressure and substrate temperature. The crystalline phases present in the films were identified with an X-ray diffractometer, equipped with a grazing incidence attachment. The angle of incidence was 3°. The preferred orientation degree in the tin oxide films and the relative cassiterite (SnO₂) proportion for each reflection were calculated from the deconvoluted X-ray peaks. It was found that the synthesis conditions have a strong influence over the growth texture and the relative cassiterite proportion over romarchite formation (SnO). To obtain tin oxide films with a high SnO₂ proportion and a high texture in reactive oxygen sputtering, were necessary, relatively high values of substrate temperature, current and oxygen pressure.