Technology of terbium monotelluride nanofilms and their electrophysical and mechanical properties


Technology of terbium monotelluride nanofilms and their electrophysical and mechanical properties/ Z. U. Jabua, A. V. Gigineishvili. / Nano Studies. – 2021–2022. – # 21/22. – pp. 125-128. – eng. Rare earth chalcogenides possess interesting electrophysical, magnetic, optical, thermal, mechanical, etc. properties. Work aims to develop the terbium monotelluride TbTe nanofilms deposition technology on various substrates and study some of their electrophysical and mechanical properties. 0.2 – 0.8 µm thick films are prepared by vacuum-thermal evaporation from two independent sources of Tb and Te. Deposition temperatures of terbium and tellurium evaporators are ~1600 and ~780 K, respectively. And distances from Tb and Te evaporators to a substrate are 23 and 49 mm, respectively. Deposition rate is of 55 Å/s. Substrate temperature changes within the range of 720 – 1150 K. Fused silica (sitall), sapphire and (111) oriented single-crystalline silicon plates are used for substrates. Substrate optimal temperature is shown to be in the range 980 – 1100 K. According to the X-ray diffraction and microanalysis, any of obtained films has the NaCl-type structure with lattice constant of 6.10 Å and contain Tb and Te, respectively, around 50.1 and 49.9 at.%. With the increase in the substrate temperature from 980 to 1100 K the film grain size increases from 23 to 49 nm. With an increase in particle size, the resistivity decreases from 4.0∙10–6 to 3.2∙10–6 Ohm∙m. All investigated films have n-type conductivity. The relative mechanical strength is investigated by the complete abrasion method on films with same thickness (of ~0.7 μm), load (of 180 g) and deposition temperature, but prepared on different substrates. Relative strength decreases in the sequence: sapphire–sitall–silicon, which is consistent with the data that the greater difference between tthermal expansion coefficients of film and substrate materials, the less relative strength of the film. Fig. 6, Ref. 6.