Epitaxial growth and metallicity of rutile MoO₂thin film

Abstract

Molybdenum oxides have various crystal structures and physical properties due to the multiple valence states of the 4d molybdenum. Among them, MoO2 has a distorted rutile structure with chemical stability and metallic behavior. In this study we grew epitaxial (100) MoO2 thin films on (0001) Al2O3 substrates. Through careful control of the Ar-partial pressure and growth temperature, we determined the optimal growth condition. From our structural assessments, MoO2 epitaxial thin films with high crystallinity can only be achieved in very narrow growth conditions such as 500˚C and 7 mTorr. The thin film prepared under optimal condition showed good metallic behavior, which was confirmed by electronic transport and optical reflectance measurements. A detailed electronic structure was also investigated by spectroscopic ellipsometry.

Study of unique and highly crystalline MoS2/MoO2 nanostructures for electro chemical applications

“…The poor conductivity of MoS 2 could mean that the transport step becomes rate-limiting, and hence compromises the overall efficiency. On the other hand, MoO 2 has been shown to possess metallic properties [40] with low electrical resistivity. The bulk and surface MoO 2 content (shown by XRD/TEM/XPS) may permit efficient charge transport and less potential drop.…”

Growth, characterization and performance of bulk and nanoengineered molybdenum oxides for electrochemical energy storage and conversion

“…An interesting feature of MoO2 is that its metallic ground state (electrical resistivity 6.9 × 10 -4 Ω cm) (Fig. 35c) [454]. The d orbital can be separated into two sub-bands, i.e., t2g and eg bands by the crystal field.…”

Enhanced Quality of Wafer‐Scale MoS2 Films by a Capping Layer Annealing Process

“…Here we show that thicker (>5 nm) precursor MoO 2 films lead to heavier texture in the converted MoS 2 films. The reason for using MoO 2 as a precursor film is because of its ability to grow continuous ultrathin film epitaxially on high‐temperature stable substrates . In order to eliminate texture from the MoS 2 films and achieve single‐crystalline MoS 2 , we developed a new process to improve the crystalline quality of the epitaxial precursor MoO 2 film.…”

“…The reason for using MoO 2 as a precursor film is because of its ability to grow continuous ultrathin film epitaxially on high-temperature stable substrates. [26][27][28] In order to eliminate texture from the MoS 2 films and achieve single-crystalline MoS 2 , we developed a new process to improve the crystalline quality of the epitaxial precursor MoO 2 film. This annealing process is henceforth referred to as the capping layer annealing process (CLAP).…”