Resistance Change Caused by Electrochemically Induced Carrier Injection in NiO Films.

Abstract

ABSTRACTIn our previous work, low resistance state (LRS) and high resistance state (HRS) areas on a nickel-oxide (NiO) film formed by applying a voltage using conductive atomic-force microscopy (C-AFM) was observed by scanning electron microscope (SEM). Comparing the observed secondary electron image (SEI) contrast to the report about the dopant-type dependence of SEI contrast reported on silicon, it was suggested that the LRS and HRS areas are, respectively, electrochemically induced p-type Ni1-xO (x > 0) and intrinsic (stoichiometric) or ntype Ni1-xO (x ≤ 0). In this paper, we verified that resistance change caused by C-AFM is due to electrochemically induced carrier injection. Reduction effect of H2annealing on the writing area, voltage dependence of depletion layer capacitance formed between the writing area and AFM-tip using scanning nonlinear dielectric microscopy (SNDM), and the effect of Schottky barrier formation between the writing area and thin metal layer on SEI contrast were investigated. Based on these results, it was clarified that the LRS and HRS areas are, respectively, p-type Ni1-xO (x > 0) and intrinsic (stoichiometric) or n-type Ni1-xO (x ≤ 0)