Thin-Film Single-Crystal Growth of BiI3 by a Hot Wall Technique

A hot wall technique has been applied to a layered compound material, BiI3, for growth of thin-film single crystals, utilizing van der Waals epitaxy on the selected layered-material substrates of PbI2 and CdI2. The thickness of the films ranged from 100 to 1000 Å. The quality of the films prepared under different growth conditions was evaluated by optical absorption spectra of a band-edge exciton, which turned out to be quite sensitive to the growth conditions of this material. The optimized conditions were established to obtain the best quality thin films, and consequently, it was found that crystal growth took place at very low temperatures around 50∼60°C.