Annealing Temperature Effect on the Surface Properties of Molybdenum Oxytelluride Thin Films

Molybdenum (oxy)telluride (MOT) thin films with varying Mo:Te ratios were fabricated by radio frequency (RF) magnetron cosputtering and annealed at 573, 773, and 973 K under Ar to examine thermal effects on their properties. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) analyses showed grain size and surface roughness increased up to 773 K, then decreased at 973 K due to volatilization of Mo and Te. Energy‐dispersive X‐ray spectroscopy (EDX) confirmed Mo’s dominant role in grain formation, while X‐ray photoelectron spectroscopy (XPS) revealed progressive oxidation with temperature. X‐ray diffraction (XRD) indicated phase evolution from amorphous to monoclinic Mo 5 TeO 16 at 573 K and orthorhombic MoO 3 at 773 K. Ultraviolet photoelectron spectroscopy (UPS) showed the work function increased up to 773 K due to oxide formation, then decreased at 973 K. Electrical conductivity was highest at 298 and 573 K, attributed to narrower bandgap phases (MoTe 2 and Mo 5 TeO 16 ). These results demonstrate that controlled annealing effectively tunes the structural and electronic properties of MOT thin films for optoelectronic and energy applications.