Phase controllable synthesis of SnSe and SnSe2 films with tunable photoresponse properties

Abstract

Nanomaterials have lots of crystal phases that are distinct from their bulk structures, and show striking structure-dependent properties, which deserve further investigation and in-depth understanding. Here, we report on the growth of highly crystalline SnSe and SnSe2 films by heating the single precursor SnSe powder via vapor deposition. The synergistic effect of heating temperature and substrate temperature in the crystal growth process determines the phase construction of samples. Proper heating temperature (650~700 °C) combined with a slow substrate temperature (~210 °C) is beneficial for SnSe2 to grow, while high substrate temperature (~380 °C) is helpful to grow SnSe. The phase diagram depending on the heating temperature and substrate temperature of samples growth has been revealed, which provides guidance for future synthesizing of the materials with a controlled stage construction. The as-grown SnSe and SnSe2 films exhibit tunable photoresponse properties, which boost the practical application of the films in photodectors.