The low resistive and transparent Al-doped SnO2 films: p-type conductivity, nanostructures and photoluminescence

• Low resistive and high transparency Al doped SnO2 films.
• Films are deposited onto ITO substrate by spray pyrolysis.
• Nanostructured films are revealed.
• p-Type conductivity is exhibited.
• Photoluminescence of films is studied.

In this work, we study the crystalline structure, surface morphology, transmittance, optical bandgap and n/p type inversion of tin oxide (SnO2). The Nanostructured films of Al-doped SnO2 were successfully produced onto ITO-coated glass substrates via the spray pyrolysis method at a deposition temperature of 300 °C. A (1 0 1) and (2 1 1)-oriented tetragonal crystal structure was confirmed by X-ray patterns; and grain sizes varied within the range 8−42 nm. The films were polycrystalline, showing a high transparency in the visible (VIS) and infrared (IR) spectra. The optical bandgap was estimated to be around 3.4 eV. The atomic force microscopy (AFM) analysis showed the nanostructures consisting of nanotips, nanopatches, nanopits and nanobubbles. The samples exhibited high conductivity that ranged from 0.55 to 104 (S/cm) at ambient and showed an inversion from n to p-type as well as a degenerate semiconductor characters with a bulk concentration reaching 1.7 x 1019 cm−3. The photoluminescence measurements reveal the detection of violet, green and yellow emissions.