Technology of therbium monotelluride nanofilms

Monochalcogenides of rare-earth elements have interesting magnetic, optical, thermal, mechanical and other properties, but not all compounds of this class are studied rather fully. TbTe belongs to such little-studied materials. The purpose of the presented work was to develop the technology of TbTe nanofilms preparation. 0.2 - 0.8 μm thick, 6 mm long and 4 mm wide TbTe films were prepared by vacuum-thermal evaporation from two independent sources of Tb and Te. Evaporation of terbium was carried out electronically by electron-beam evaporation and tellurium by the Joule evaporator. In the course of a dusting temperature of the evaporator of terbium equaled 1600 K, and a tellurium - 780 K. Distances from Tb and Te evaporators to a substrate made respectively 22 mm and 43 mm. Speed of a dusting of films was equal to 55 Å / s. Temperature of a substrate changed within 720 - 1150 K. As substrates we used glass-ceramic, fused silica, sappire and (111) - oriented single-crystal silicon plates. Optimum temperature of a substrate is 1110 K, above this temperature the besieged atoms come off a substrate, and below the temperature the adsorbed atoms create islands of various thickness. According to the x-ray analysis a film had structure of NaCl type with lattice constant 6.10 Å and according to the X-ray microanalysis films contained 50.1 at. % of Tb and 49.9 at. % Te. The picture of TbTe surface has been removed by electronic-scanning microscope. This process has shown that the film contains characteristic elements with the size range within 24 - 49 nm, that allows to draw a conclusion that we have nano-dimensional object. (author)