Dielectric properties of sol-gel derived ZnO thin films

Sol-gel derived ZnO thin films were prepared on platinized Si wafers and fired to temperatures ranging from 550C to 700C. Multiple spincoating was performed with an intermediate firing at 400C between coatings to obtain films up to 6000 A thick. Top Pt electrodes were sputtered to form monolithic capacitors. Dielectric characterization indicated dielectric constants as large as 24, twice the highest value reported previously. The leakage currents decreased with increasing firing temperature. XRD indicated that the films consisted of crystalline wurtzite films at firing temperatures as low as 400C and that the c-axis orientation increased with increasing firing temperature. Piezoelectric characterization indicated d₃₃ values as large as 17 pm/V, which is larger than any previously reported value for ZnO films