Effect of annealing in an inert atmosphere on the electrical properties of crystalline pentacene films

The results of a study of the effect of annealing at 150$^{\circ}$C in an inert atmosphere (Ar + 5% H$_2$) on the electrical properties of organic field-effect transistors based on pentacene are presented. Crystalline pentacene films with a thickness of 95 $\pm$ 5 nm were obtained using thermal vacuum deposition. The transfer and output characteristics of field-effect transistors before and after annealing for 15 hours are investigated. It was found that as a result of heat treatment, the hole mobility in the saturation regime increased by an average of 30%, and the threshold voltage decreased approximately two times. According to the data of atomic force microscopy, annealing led to a more than twofold decrease in the surface roughness of pentacene films, as well as to a noticeable enlargement of grains, which led to a decrease in the concentration of traps for hole electric transport in the channel of the field-effect transistor.