Crystalline structure and thermoelectric properties versus growing conditions of sputtering-deposited (Bi1-xSbx)2Te3 films with 0⩽x⩽0.85

(Bi_1-xSb_x)₂Te₃ films of about 1 μm thickness were deposited on Kapton substrates by means of DC magnetron sputtering. Four different targets were used with compositions according to (Bi_1-xSb_x)₂Te ₃+20 at% Te and x=0, 0.5, 0.75 and 0.85. The substrate temperature T_s and of a hot-wall environment T_e were altered in the range of 220...320°C and 150...390°C, respectively. Composition and crystalline structure were studied using WDX, SEM and XRD. Films grown at T_s<290°C had rough surfaces and weak texture. Above T_s=290°C the films were strongly (0 0 n) textured and had smooth surfaces. Annealing at 300 or 350°C increased the size of the crystallites but their orientation was unchanged. This behaviour was independent of the composition x. The transport properties depend significantly on Sb-Bi ratio x, substrate and environment temperatures and annealing. High carrier mobilities could only be achieved together with low carrier concentrations and at T _s≈250°C after annealing. Films best suited for thermoelectric applications (highest power factor at room temperature) had the composition (Bi_0.15Sb_0.85)₂Te ₃, the conductivity σ=1140 Ω^-1 cm^-1, the carrier mobility μ=360cm²/Vs and the Seebeck coefficient S=182 μV/K