Physical properties of hot wall deposited Sn$_{1-x}$Pb$_{x}$S thin films

Thin films and nanorods of Sn$_{1-x}$Pb$_{x}$S (0.00$\le x\le$ 0.45) with orthorhombic crystal structure and c-axis oriented perpendicular to the substrate surface were grown by hot wall vacuum deposition (HWVD) method. The nanorods grew via a self consuming vapor-liquid-solid (VLS) mechanism by means of Sn-droplets onto the surface of an underlying thin film. The former one consists of stacked blocks with their c-axis always parallel to the growth direction. However, each block is alternately rotated around the [001] against its underlying and subsequent one. As revealed by composition analysis, there is no composition gradient across or within the nanorods and the underlying film. The rods were about 500 nm high and 250 nm in diameter. The droplet at the top of rods consists of Sn with small trace of Pb and S. The density of rods, arranged like a lawn, depends on the metal ratio and substrate temperature. The as-grown Sn$_{1-x}$Pb$_{x}$S samples showed p-type electrical conductivity. Increasing the lead atom concentration results in a decreased Seebeck coefficient and lower conductivity.