The effects of zinc substitution on the electrical properties of MgNb₂O₆ thin films

The effects of zinc substitution on the electrical properties of sol-gel derived MgNb₂O₆ (Mg_1-xZn_xNb₂O₆; MZ_xNO) thin films were investigated. Accordingly, the experimental results revealed that the optimal optical and electrical properties of the devices can be obtained for specimen with x = 0.2. The dielectric constant, average transparency and optical band gap of the devices at 400°C annealing are 21.2 (@1 MHz), ~80% and 4.86 eV, respectively. The results indicated that the electrical properties of the sol-gel derived MgNb₂O₆ thin films are tuneable based upon the variation of zinc content. More importantly, the fabrication temperature of the MZ_0.2NO thin films is 100°C lower than the bending point of the glass substrate making it suitable for practical applications. With the increase of the applied electric field, the leakage conduction mechanisms of the Al/MZ_xNO/ITO devices are mainly controlled first by ohmic conduction at low electric field, changes to space-charge-limited conduction (SCLC) and then FN tunneling at high electric field. Moreover, the critical electric field strength of the conduction mechanisms is also a function of the zinc content.