Electrical characteristics of zinc oxide implanted with a high dose of 3d-metal ions on direct and alternating current

Monocrystalline plates of zinc oxide have been implanted by high doses (1,5×10¹⁷ cm^-2) of Mn⁺, Fe⁺, Co⁺, Ni⁺ ions with the energy 40 keV at the ion current density 4,0 μA/cm² to modify their electron-transport properties. The temperature dependence of resistance in the temperature range T = 300... 2,5 K as well as DC and AC electrical characteristics have been measured in the frequency range from 25 Hz to 1 MHz at T = 300 K. The transition from insulating to metallic regime of conductivity is observed only for implantation of cobalt ions. At low temperatures on the insulating side of the insulator-to-metal transition the charge transport is determined by the electrons tunneling through fluctuations of conduction band in the heavily disordered modified layer of a semiconductor. On the metallic side of the insulator-to-metal transition the processes of weak localization and electron-electron interactions are dominant. (authors)