Ultra-thin MoO₃ film goes wafer-scaled nano-architectonics by atomic layer deposition

From the technical and design points of view, it is quite difficult to maintain the integrity of nano-films during the deposition process to fabricate practical devices based on ultra-thin semiconductor films. Thus, defect-free wafer-scaled development of ultra-thin quasi two-dimensional (2D) oxide semiconductor films represents serious challenges. Plasma-enhanced atomic layer deposition (PE-ALD) made it possible to fabricate ultra-thin MoO₃ nano-films (4.6 nm) over the wafer-scaled granular Au electrode. The detailed ALD recipe for ultra-thin MoO₃ film was established and verified. The C₁₂H₃₀N₄Mo and O₂ plasma were used as Mo precursor and oxygen source, respectively. The growth of crystalline phases was observed when the ALD temperature of 250 °C was employed. Higher ALD temperature resulted in an increase of growth rate over Au substrate (1.21 Ǻ/cycle). The precise recipe design enabled the scalable fabrication of environmental sensors based on ultra-thin MoO₃ films with precise thickness controllability. Electrochemical sensors based on the fabricated MoO₃ nanostructures demonstrated reliable performance to hydrazine (N₂H₄) detection.