Implant isolation of ZnO

We study ion-irradiation-induced electrical isolation in n-type single-crystal ZnO epilayers. Emphasis is given to improving the thermal stability of isolation and obtaining a better understanding of the isolation mechanism. Results show that an increase in the dose of 2 MeV O ions ~up to ;2 orders of magnitude above the threshold isolation dose! and irradiation temperature ~up to 350 °C) has a relatively minor effect on the thermal stability of electrical isolation, which is limited to temperatures of ;300– 400 °C. An analysis of the temperature dependence of sheet resistance suggests that effective levels associated with irradiation-produced defects are rather shallow (,50 meV). For the case of implantation with keV Cr, Fe, or Ni ions, the evolution of sheet resistance with annealing temperature is consistent with defect-induced isolation, with a relatively minor effect of Cr, Fe, or Ni impurities on the thermal stability of isolation. Results also reveal a negligible ion-beam flux effect in the case of irradiation with 2 MeV O ions, supporting high diffusivity of ion-beam-generated defects during ion irradiation and a very fast stabilization of collision cascade processes in ZnO. Based on these results, the mechanism for electrical isolation in ZnO by ion bombardment is discussed. © 2003 American Institute of Physics. @DOI: 10.1063/1.1542939#