Effect of Sn-substituted Ga and In dopant content on the structural, electrical, and optical properties of p-type X-doped SnO2 (X = Ga and In) films: Testing the photoelectronic effect of X-doped SnO2/n-Si junctions

[Display omitted] •The optimum X3+–Sn4+ substitution (X = Ga and In) favored the best p-type conductivity.•The lowest resistivity of 7.51% for the Ga-doped SnO2 film was due to the hole concentration.•The lowest resistivity of 6.29% for the In-doped SnO2 film was optimized by the hole mobility.•The optimum In content in the SnO2 lattice reduced the lattice distortion, but Ga did not.•The I–V characteristics of the In/XTO/n-Si/In devices under illumination were photodiode-like. To achieve the best p-type conductive properties of X-doped SnO2 (X = Ga, In) SnO2 film, a 9% wt X2O3 in SnO2 target is the best content for substitution at X sites in the SnO2 host lattice by X dopant where optimum In content replaces Sn, eliminating the lattice distortion in undoped SnO2 film. Optimum Ga content that replaces Sn enhances the lattice distortion but does not break the host lattice. The Ga3+–Sn2+ and In3+–Sn2+ substitution was verified using measurements such as X-ray photoelectron spectroscopy, photoluminescence, and ultraviolet-visible spectroscopy; the data for the (110) to (101) tetragonal rutile lattice plane changes indicated this replacement. The best p-type conductive properties achieved were 3.0 × 10−1 Ω cm, 6.20 × 1018 cm−3, and 3.01 cm2 V−1 s−1, respectively, for GTO. The respective values of the TIO films were 2.6 × 10−1 Ω cm, 1.24 × 1018 cm−3, and 19.35 cm2 V−1 s−1 for the resistivity, hole concentration, and hole mobility, respectively. The I–V characteristics of the In/p-GTO/n-Si/In and In/p-TIO/n-Si/In devices under illumination showed the p-type conductive properties of the GTO and TIO films.