Effect of Sm doping ZnO nanorods on structural optical and electrical properties of Schottky diodes prepared by chemical bath deposition

In this study, pure and Sm doped ZnO nanorods from 0.0 to 5.5 at% were synthesized using the chemical bath deposition method at 90 °C. The effect of Sm doping of ZnO nanorods on their structural, morphology and optical properties were investigated. X-ray diffraction patterns revealed that Sm had been successfully incorporated into the ZnO lattice and no other impurities or Sm oxide phases were detected. Field emission scanning electron microscopy images showed that the growth rate of the nanorods was suppressed by Sm doping. Room temperature Raman scattering spectroscopy revealed that the relative intensity of E₂(high) mode decreased and shifted slightly towards a lower wavenumber in Sm doped ZnO when compared to the undoped ZnO nanorods. The photoluminescence spectrum of as-synthesized Sm-doped samples measured at room temperature shows that the UV emission is slightly red shifted and the green-yellow emission of the visible emission is enhanced, when compared to undoped samples. Photoluminescence studies also revealed the good crystal quality of the as-synthesized samples as all sample shows strong ultraviolet and weak deep-level emission peaks. The as-synthesized samples were also characterized using X-ray photoelectron spectroscopy that revealed the presence of Zn and O in all samples and a small amount of Sm in 5.5 at% Sm doped ZnO was detected. Furthermore, the current-voltage characteristics of a fabricated Schottky diodes showed a good rectifying behavior when ZnO doped with Sm at 1.5 at%. The obtained Schottky barrier height for pure and Sm doped ZnO nanorods were 0.55 eV and 0.72 eV, respectively.