Compositional and electrical modulation of niobium oxide thin films deposited by plasma-enhanced atomic layer deposition

Abstract

Composition-modulated niobium oxide thin films were deposited by plasma-enhanced atomic layer deposition using NbF5, hydrogen plasma and ozone as the precursor, a reducing agent and an oxidant, respectively. For composition control of the niobium oxide thin films, a super-cycle was adopted, which was composed of n cycles of the metal deposition step and one cycle of the oxidation step. NbO2 and Nb2O5 phase components coexisted in the NbOx thin films, and the phase composition ratio of Nb2O5 and NbO2 could be modulated from approximately 80:20 to 40:60 through control of the cycle ratio. Furthermore, the optical bandgap and electrical resistivity decreased from 3.91eV to 2.19 eV and from 6.5 x10(4) CI cm to 3.1 x10(-1) Omega cm with increasing the cycle count for the Nb metal deposition step, respectively. Consequently, we could effectively modulate the electrical properties of NbOx thin films via compositional modulation.