Phosphorus (P) ion implantation was employed to study the fluence-dependent polymorphic evolution in α-V2O5 thin films grown by pulsed laser deposition. Grazing incidence X-ray diffraction confirms the orthorhombic α-V2O5 phase in pristine films, and implantation introduces lattice distortion and alters the preferred crystal orientation. Raman spectroscopy indicates the appearance of β-V2O5 related vibrational modes at lower fluences, suggesting a partial α→β phase transformation, followed by partial recovery toward the α-phase at the highest fluence due to defect recombination. Optical measurements reveal a noticeable band gap reduction from ∼2.4 eV (pristine) to ∼1.97 eV at lower fluences, mainly attributed to implantation-induced oxygen vacancies and defect states, whereas a slight blue shift at the highest fluence is associated with defect annihilation. Deconvoluted photoluminescence spectra further support variations in oxygen-vacancy-related emission bands. Synchrotron-based X-ray absorption spectroscopy shows a fluence-dependent variation in the t2g/eg orbital intensity ratio, indicating changes in V–O hybridization and local symmetry accompanying the α↔β structural evolution. Monte Carlo SRIM simulations further validate the atomic displacement processes responsible for defect formation and phase modification. Overall, 100 keV P-ion implantation enables controlled tuning of defect density and polymorphic phase behavior in V2O5 thin films, highlighting their potential for multifunctional gasochromic and optoelectronic applications.
Malik et al. (Tue,) studied this question.