Mo nitrides and carbonitrides via metallic phase transition of MoO3 films using ammonium salt precursors in chemical vapor deposition

Abstract

Transition-metal-based nitrides and carbides have been widely studied for various applications because of their excellent mechanical, electrical, and catalytic properties. Although outstanding performances of Mo nitride and carbonitride synthesized by chemical reaction methods have been reported recently for catalytic applications, a metallic phase transition method for pre-deposited MoO3 precursor films, which is suitable for application to Si or metallic substrates, has rarely been reported. Herein, we investigate Mo nitride and carbonitride thin films synthesized via nitriding and carbonitriding of MoO3 films using two types of ammonium salt precursors, urea and ammonium carbonate (AC), in the chemical vapor deposition (CVD) process. The phase-changed crystalline films of Mo carbonitride via the urea reaction and Mo nitride via the AC reaction were determined to be MoC0.5N0.5 and MoN by X-ray diffractometry, respectively. Nevertheless, amorphous states of carbons and their related compounds, unreacted residual MoO3, and incompletely reacted MoO2 remained in the films, as determined by other thin film analyses. When the residual MoO2 was minimal, the films exhibited the lowest electrical resistivity, i.e., ∼10−4 Ω·cm for Mo carbonitride and ∼10−3 Ω·cm for Mo nitride, implying an optimum metallic phase transition. Our results pave the way for the nitriding and carbonitriding of transition metal oxides using ammonium salt precursors for a one-step reaction in the CVD process.