Work functions of thin LaB 6 films

Abstract

LaB 6 thin films were prepared at elevated temperatures by electron beam deposition in vacuum and were stabilized by annealing at 1100 K for 60 min. Their electron emission characteristics were investigated by the thermionic emission method. The work functions of the films fabricated at 300, 750 and 1000 K had values of 2.7–2.8 eV. The work functions of the films formed on tilted substrates (45° and 80° to the normal direction) at 750 K were also measured, and they had values of ∼ 2.7 eV. X-ray diffraction peak positions showed that stress in the films changes from tensile to compressive with increasing substrate tilt angle, and at 45° it is nearly zero. It is found that substrate temperature and film strain have little influence on the work function.