Preparation and characterization of nanostructures of in-doped ZnO films deposited by chemically spray pyrolysis: Effect of substrate temperatures

• Important report on simplified spray deposited In-doped ZnO films.
• PL, electrical and structural results are corroborated with each other.
• Enhancement of electrical parameters by means of indium-doping.
• Smooth nanostructures are grown along c-axis.
• The linear dependence of physical properties on the substrate temperature of as-grown films is confirmed.

We deposited undoped (ZnO) and indium-doped ZnO (IZO) films onto glass substrate via ultrasonic spray pyrolysis technique. The variation in structural, surface morphology, electrical, optical and photoluminescent properties as a function of substrate temperature is investigated. X-rays pattern confirms that as-synthesized IZO phase is grown along a (002) preferential plane. Nanosized grains (<50 nm) are determined by X-ray analysis. Morphology of as-grown films shows broadened nanostructures which have grown along c-axis and nanostructures are found to be smooth (RMS∼60 nm). Study by spectrophotometer reveals that the as-grown films are highly transparent in the visible and IR spectra (T ∼ 88%), and that the bandgap is slightly narrowed (3.17 eV). Electrical measurements confirm the enhancement of conductivity, ρ < 1 Ω cm, due to indium incorporation into the starting solution. An electron concentration of 1017 cm−3 and a mobility of 3 cm2/Vs are found for IZO films grown at 400 °C. The photoluminescence analysis demonstrates strong yellow (2.1 eV) and blue (2.8 eV) light and weak green (2.3 eV) emissions.