Formation of Impurity Accumulations in Silicon Doped with Nickel and Copper

The paper presents the results of structural studies of silicon doped with nickel and copper, obtained using electron microscopy and X- ray diffraction analysis. The samples under study were obtained by simultaneous diffusion doping of single-crystal silicon with impurity atoms of nickel and copper at a temperature of T = 1473 K for 5 hours. Single- crystal n-type silicon with a resistivity of 0.3 Ohm·cm, grown using the Czochralski method, was used as the initial sample. After diffusion annealing, the samples were cooled to room temperature at a rate of 200 K/s. Structural studies were carried out using a modern JEOL electron probe microscope, which makes it possible to determine the elemental composition of various bulk impurity accumulations formed during the doping of semiconductor materials and obtain their images. X-ray diffraction analyzes of silicon samples with impurity accumulations were carried out using a modern Malvern Panalytical Empyrean X-ray diffractometer. It has been revealed that the formation of various impurity accumulations in the bulk of silicon, during high-temperature diffusion doping, leads to distortion of the crystalline structure of silicon. As a result, a decrease in the average crystallite size L and an increase in the interplanar distance – d are observed compared to the original sample. It was discovered that in the process of doping with silicon, nickel and copper, two- or three-component compounds are formed in the bulk of the samples with the participation of atoms of the main matrix element of silicon, as well as nickel and copper impurities. In addition, the formation of compounds of silicon atoms with atoms of technological impurities, such as carbon and oxygen, is observed, which shows their activity in the process of diffusion doping.

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