High-quality thin film growth of the weak topological insulator BiSe on Si (111) substrates via pulsed laser deposition

In this work, we report the growth of high-quality BiSe thin films deposited on Si (111) substrates at different temperatures via pulsed laser deposition. We observe poor sample quality at a low substrate temperature (Tsub=175°C), and as the substrate temperature increases, the crystallinity of the samples increases. At a substrate temperature, Tsub=250°C, BiSe Raman modes (modes centered around 97.6 and 112.9 cm−1) start to emerge with less intensity and evolve with the increase in the substrate temperature and at Tsub=325°C closely match with that of single crystals. These modes correspond to the vibrations of Se-atoms from the Bi2Se3 quintuple layers and Bi-atoms from the Bi-bilayer. By carefully investigating the structural properties and the Raman modes of BiSe thin films at each substrate temperature, we provide an optimal condition to grow high-quality thin films of BiSe by pulsed laser deposition.