Field effect transistors with layered two-dimensional SnS2−xSex conduction channels: Effects of selenium substitution

A thorough characterization of field effect transistors with conduction channels made of SnS2−xSex nanocrystals having different selenium content is presented. The main effect of increasing the selenium content is a suppression of the drain-source current modulation by the gate voltage. The temperature dependence of SnS2−xSex conductivity for all compositions is characterized by an activation energy that gradually decreases with x. A simple donor model, with parameters of SnS2 and SnSe2 deduced from density functional theory, suggests that the change in the activation energy is mostly due to enhanced dielectric constants that accompany the band gap reduction in SnS2−xSex.