Nanoscale Conductive Channels in Silicon Whiskers with Nickel Impurity

The magnetization and magnetoresistance of Si whiskers doped with to boron concentrations corresponding to the metal-insulator transition (2 × 10¹⁸ cm^-3 ÷ 5 × 10¹⁸ cm^-3) were measured at high magnetic fields up to 14 T in a wide temperature range 4.2-300 K. Hysteresis of the magnetic moment was observed for Si p-type whiskers with nickel impurity in a wide temperature range 4.2-300 K indicating a strong interaction between the Ni impurities and the possibility of a magnetic cluster creation. The introduction of Ni impurity in Si whiskers leads to appearance and increase of the magnitude of negative magnetoresistance up to 10% as well as to the decrease of the whisker resistivity in the range of hopping conductance at low temperatures. The abovementioned effects were explained in the framework of appearance of magnetic polarons leading to modification of the conductive channels in the subsurface layers of the whiskers.