Influence of Accumulation of Impurity Atoms Ni and Fe on the Electrophysical Properties of Si Single Crystals

The article discusses the processes of formation of impurity accumulations in silicon, simultaneously doped with impurity atoms of nickel and iron at a temperature of T = 1473 K. The structural structures and elemental composition of impurity accumulations, which have different morphological parameters, are studied. The results of structural analyzes showed that the formation of any massive accumulations of impurity atoms was not observed in the volume of the initial samples. Unlike the original samples, in the volume of n-Si<Ni, Fe> samples, the formation of accumulations of impurity atoms of various geometric shapes is observed, the sizes of which reach up to several hundred nanometers. It has been revealed that in the volume of impurity accumulations, in addition to atoms of the matrix element silicon and the main impurities of nickel and iron, there are also atoms of so-called technological impurities such as carbon and oxygen. Analyzes of the chemical composition of an impurity accumulation with a spherical shape, the diameter of which is 400 nm, showed that in the central region of this impurity accumulation the percentage of impurity Ni atoms is 30.76 %, and iron atoms are 16.34 %. Also presented are the results of studies of the effect of thermal annealing on the resistivity of n-Si<Ni, Fe> samples at temperatures T = 673-1273 K in a time interval of 10-120 minutes, followed by sharp quenching. As it turned out, in the dependences of the relative resistivity of n-Si<Ni, Fe> samples on the duration of the annealing time, a certain tendency is observed, according to which, with increasing annealing temperature, the maximum in the dependence curves occurs at a shorter annealing time. Using electron microscopy, structural analyzes of the state of impurity accumulations before and after exposure to thermal annealing were carried out.