Barium Zirconate Nickelate as the Gate Dielectric for Low-Leakage Current Organic Transistors

Abstract

High- $\kappa $ barium zirconate nickelate (BZN) gate dielectric layer was prepared through the low-temperature sol–gel method and was used in pentacene-based organic thin-film transistor (OTFT) applications. In comparison with its barium zirconate oxide (BZO) counterpart, experimental results show that the threshold voltage of the BZN-based OTFTs decreases from −2 to −1.1 V, the gate leakage decreases from 10−8 to 10−12 A, the carrier mobility increases from 2.1 to 5.2 cm2/Vs, and the subthreshold swing decreases from 2.4 to 0.4 V/decade. The effect of Ni on device characteristics is discussed in this paper. Ni(II) acetylacetone possesses two pairs of symmetrical bidentate ligands, which can chelate with Zr ion to smoothen surface roughness. The dielectric constant can be increased. The enhancement of mobility is partly attributed to the smoother surface to reduce the scattering effects of the carrier. In addition, the improved film quality may also increase the barrier height and reduce the leakage current, which enhances the ON/ OFF ratio through the chelate effect due to the addition of Ni in BZO. Furthermore, excellent operation stability can be achieved.