Effect of dielectric thickness on MgZnO Thin Film Transistor characteristics

Abstract

From past ten years, low-k dielectric was used as dielectric material in Thin Film Transistors Technology.Reduction of dimension of device can be done with the reduction the thickness of dielectric material and active layer. Due to reduction in thickness of dielectric material capacitances increases therefore drain current increases. But further more reduction in dielectric material leads to leakage current which effect other parameter like threshold voltage. To enhance performance of transistors without reduction in thickness of dielectric material use high-k dielectric material so overall capacitances increases and decrease leakage current. In this paper the parameters of the MgxZn1−x thin film transistors are compared. Composition of Mg in ZnO used because high direct bandgap (7.7 eV). Due to composition of Mg into ZnO that affects the electrical parameter of a transistor. MgxZn1−x (x = 20% and 1-x = 80%) Thin film transistor’s electrical performance with high-k (Al2O3(K ∼ 9)) dielectric materials thickness is measured. Variation in thickness of high-k dielectric is taken as 150 nm, 100 nm, 50 nm, 20 nm. Electrical characteristics are good for 20 nm thickness of Al2O3 dielectric material. Optimized electrical parameter of transistor like threshold voltage, mobility, and on/off ratio are 0.59 V, 9.62 cm2/V.s, and 1010 observed after simulation on TCAD. Results shows that this type of results for Thin film Transistors are used in photodetector application.