Nanocrystalline Zn_1−xMn_xO thin film based transparent Schottky diodes

Highly transparent and nanocrystalline Zn_1−xMn_xO (x = 0, 0.008, 0.017, 0.046) thin films have been synthesized by sol–gel spin coating technique on glass and SnO₂ coated glass substrates. The microstructural and compositional analyses confirm the incorporation of Mn in hexagonal ZnO lattice without affecting its structure. Zn_1−xMn_xO thin films are highly transparent in the visible region of electromagnetic spectrum. The optical band gap, estimated from the transmittance spectra, decreases from 3.32 to 3.21 eV with the increase in Mn content in ZnO films. Photoluminescence study reveals that Mn introduces more defects in ZnO suppressing the excitonic recombination by the defect center (oxygen vacancy) induced recombination. The non-linear current–voltage characteristics at room temperature reveal Schottky barrier junction formation of Zn_1−xMn_xO films with Ag. The diode parameters, extracted from the thermionic emission model, vary with Mn incorporation in ZnO. Both the ideality factor and potential barrier height decrease from 6.5 and 0.63 for pure ZnO to 4.7 and 0.54 respectively, for Zn_0.954Mn_0.046O film. The series resistance that arises from the defect distributions at the interface and effects the charge transport through the junction, also decreases for higher percentage of Mn in Zn_1−xMn_xO thin films. - Highlights: • Mn doped transparent ZnO thin film synthesis using sol–gel spin coating • Particle size and optical band-gap decreases with increasing Mn doping. • Absence of any secondary phase upto 4.6 at.% of Mn which substitutes Zn sites in ZnO lattice • Interesting Schottky diode characteristics with Ag contact • Ideality factor and barrier height decreases with increasing Mn content.