Observation of surface excitons in BiI 3 thin films single crystals grown by the hot wall technique

Abstract

We have observed a surface exciton transition in the absorption spectra of thin films single crystals of BiI 3 grown by use of a recently developed hot wall method. The energy position of the surface exciton was 50 meV higher than that of the direct exciton. The intensity and the half-width of the surface exciton were evaluated to be 0.1 O.D. and less than 20 meV, respectively.