THE CRYSTAL STRUCTURE OF THE BASIC LAYERS OF CADMIUM TELLURIDE IN PLANAR ELEMENTS FOR PROTECTING MICROWAVE EQUIPMENT FROM ELECTROMAGNETIC PULSES

To create the physical basis of the industrial technology of planar protection elements, base layers of cadmium telluride, which were obtained by the method of thermal vacuum evaporation at different substrate temperatures on polycore plates with a molybdenum interlayer, were investigated using the X-ray diffractometric method. Temperature intervals corresponding to a qualitative change in the crystal structure of cadmium telluride films were determined. It is shown that the cadmium telluride films obtained at a substrate temperature that does not exceed 100°C contain only the hexagonal metastable phase, have a predominant orientation in the [002] direction, the level of microdeformation is 0.088 - 0.110, the size of the coherent scattering regions is 15.6 - 21.5 nm. The determined periods of the hexagonal crystal lattice a = 4.586 Å and c = 7.505 Å indicate the presence of significant tensile macrodeformations. An increase in the deposition temperature to 200°C leads to the appearance of a stable cubic phase oriented in the [111] direction along with the metastable hexagonal phase of cadmium telluride. At the same time, the orientation of the hexagonal phase in the [002] direction decreases from GH = 1.74 to GH = 1.45. The appearance of the cubic phase also leads to a decrease in microdeformations and the dimensions of the coherent scattering regions of the hexagonal phase to 0.029 - 0.043 nm and 12.1 - 15.8 nm, respectively. A further increase in the temperature of the substrate leads to the formation of cadmium telluride films in which there is only a stable cubic phase without a preferred orientation. At the same time, an increase in the temperature of the substrate to 300°C leads to a decrease in the macrodeformations of the cubic phase, which is evidenced by the approach of the period of the crystal lattice to the theoretical value: from a = 6.4870 Å to a = 6.4858 Å. Thus, it was experimentally shown that in order to ensure stable initial parameters of protection elements, the production of cadmium telluride films must be carried out at a substrate temperature of 300°C, as this prevents the presence of degradation processes due to the thermodynamically activated transformation of the metastable hexagonal phase into a stable cubic phase.