The role of pH solution in depositing MoO3 film by spray pyrolysis as hole selective contact on silicon-based heterojunction devices

•The solution pH influences structural, morphological, and electrical properties of oxides films.•X-ray diffraction data shows that the crystallite size increases with the pH solution.•The diode properties of the films: barrier height and ideality factor changes with the pH solution. The thermal evaporation technique has been frequently used for the deposition of sub-stoichiometric molybdenum oxide (MoO3) films. This approach requires a high temperature, which limits the control of MoO3 stoichiometry and affects its conducting mechanism. In this study, a spray pyrolysis technique (SPT) has been used to grow MoO3 film by varying the pH solution. The formation of an orthorhombic lamellar crystal structure with (0 k0) preferred orientation was realized using X-ray diffraction analysis. FESEM analysis confirmed pH solution dependence on the particle growth properties. The vibrational peaks of the Raman spectra justified the presence of the sub-stochiometric α-MoO3 film. The p-n heterojunction diodes constructed based on the Ag/MoO3/n-Si/Al showed a well-defined rectifying behaviour with the film deposited at 0.6 pH solution.