Effect of Hf doping content on the structure, optical and electrical properties of flexible Hf Zn1-O thin films by sol-gel method

Impedance Spectroscopy and Structural Characterization of Nanostructured ZnO and Hf-Doped ZnO Ceramics

“…29,30 Therefore, Hf doping suppresses ZnO crystal growth, resulting in increased surface smoothness. 30,31 The FESEM results are consistent with the crystal size change in the XRD results.…”

“…The small radius of the semicircles indicates the lower resistance, the faster charge transfer at the interface. 31,50 In Nyquist plots of ′ ′ Z versus ′ Z , it is known that while the grain and grain boundary effect is effective in high frequency regions, the grain boundary effect is more effective in low frequency regions. For a Debye-type relaxation, a perfect semicircle centered on the Z′ axis is observed.…”

“…To fit the models to impedance data, constant phase elements (CPE), which are identified as an imperfect/faulty capacitor are often used. 31,54,[58][59][60] The equivalent circuit for 300 K,…”

“…Some studies have been reported on Hf-doped ZnO thin film structures with unique electrical properties expecially 0%-3%Hf doped. For example, it was observed that minimum resistivity value of 1.2 × 10 −3 Ω cm and transmission of higher than 80% for 0.5 at% Hf doped ZnO from (0, 1, 3, 5, 7, 10 at%) Hf-doped ZnO samples by pulsed laser deposition, 29 it was revealed 3.3 at%Hf doped ZnO has lowest resistivity 6.7 × 10 −4 Ω.cm and transmittance value of %77 from 0< × ⩽6.7 at% (0, 1, 3, 5, 7 at%) Hf-doped ZnO samples using atomic layer deposition, 30 it was revealed that 3 at%Hf doped ZnO has minimum resistivity value of 6.3 × 10 −2 Ω.cm and crystallsize value of 65 nm from (0, 1, 3, 5, 7 at%)Hf-doped ZnO samples while the resistivity was 38 × 10 −3 Ω.cm, transmission of higher than 60%-70% and crystallsize value of 81 nm for un-doped ZnO by solgel technique, 31 it was shown that 3 at%Hf doped ZnO has minimum resistivity value of 5.6 × 10 −3 Ω.cm from (0, 1, 3, 5, 7 at%) Hfdoped ZnO samples while the resistivity of un-doped ZnO was 38 × 10 −3 Ω.cm by sol-gel technique, 32 it was obtained that 1 at%Hfdoped ZnO has ultra-low resistivity value of 4.2 × 10 −3 Ω.cm and they observed that strong green emission peak at room temperature using the sol-gel method. 33 Apart from these studies of Hf-doped ZnO thin films, to our knowledge, few studies have been reported on the characterization of Hf-doped ZnO nanopowders or bulk ceramic samples.…”