Solution processed low band gap ion-conducting gate dielectric for low voltage metal oxide transistor

Abstract

Low band gap ion conducting Li2ZnO2 thin film has been synthesized by low cost solution processed technique and has been employed to fabricate low operating voltage metal oxide thin film transistor (TFT) with high device performance. Li2ZnO2 is a known ion conducting oxide material, generally used as solid state electrolyte in different applications including fuel cell and Li ion battery. Instead of having low band gap, Li2ZnO2 thin film shows very insulating behavior and low leakage current. Additionally, it shows high dielectric constant (κ) that originated from the conducting nature of its Li+ ion, serve as a gate dielectric for low operating voltage metal oxide TFT. In addition to this dielectric, tin oxide (SnO2) semiconductor channel has also been deposited in solution processed technique in the bottom gate top contact TFT structure. Such kind of TFT device requires only 2.0 V or less drain voltage with the gate bias in the range of 2.0-V to saturate the drain current. The extracted carrier mobility, on/off ratio and subthreshold voltage for Li2ZnO2 based TFT are 23 cm2 V−1 s−1, 6 × 103 and 390 mV dec−1 respectively. The device parameters have been compared with sol-gel derived reference Li2O dielectric, which clearly indicates the superiority of Li2ZnO2 dielectric in the performance of TFT. © 2018 Elsevier B.V.