Controlled p-type doping in (111)NiO epitaxial films through ions irradiation

The effect of irradiation by Ar ions with energy of 300 keV and different fluences (F) on the structural and transport properties of (111) nickel oxide (NiO) epitaxial films is investigated. It has been found that the crystallinity and surface morphology of the films remain mostly unaffected upon irradiation even at the highest fluence of 1×1016 ions/cm2. The study further shows the development of a compressive strain in the irradiated films, which has been attributed to the formation of vacancy type defects in the lattice. Transport studies on the field effect transistors fabricated on both the irradiated and unirradiated samples reveal the enhancement of both mobility and concentration of the holes upon irradiation. While the concentration enhancement can be attributed to the Ni-vacancy type defects, which are predicted to act as shallow acceptors in NiO, the increase in mobility can be explained in terms of the improvement of crystallinity of the film upon irradiation. Our study thus offers a viable pathway for area-selective p-type doping via controlled Ni-vacancy formation.