Influence of Dielectric and Active layer Thickness on MgZnO Thin Film Transistor Electrical Characteristics

Open Access

Year : 2023 | Volume : 11 | Special Issue : 05 | Page : 17-26

    Manju Choudhary

  1. Associate Professor, Swami Keshvanand Institute of Technology, Management & Gramothan, Rajasthan, India


From last decades, Thin Film Transistors Technology uses low-k dielectric material as an insulator. Insulator thickness plays an important role in device dimension. The insulating layer also known as the gate oxide separates the gate electrode from the channel region of the transistor. If the insulating layer is too thin, there is a greater chance that electrons can tunnel through the oxide layer, leading to leakage current. To mitigate this issue, various techniques are used such as the introduction of high-k dielectrics, which have a higher dielectric constant, allowing for thicker insulating layers to be used while maintaining the same capacitance. To gain better transistor characteristics without reducing oxide thickness use high-k dielectric instead of SiO2 to reduce leakage current and improve gate oxide capacitance. In this work the electrical performances of the MgxZn1−xO Thin film transistors are analyzed and compared. Mg is a high direct bandgap (7.7 eV) material that alter the electrical and optical properties of a transistor. MgxZn1−xO (20% of Mg and 80% of ZnO) Thin film transistor’s electrical characteristics with different dielectric materials and variations in channel thickness is measured. First variation with different insulator e.g., SiO2(K ∼ 3.9), Si3N4(K ∼ 7.9), Al2O3(K ∼ 9), and HfO2(K ∼ 25) dielectrics are done. Then thickness of the active layer is varied as 30 nm, 50 nm, and 70 nm for all the four dielectric materials. Drain characteristics and transfer characteristics are good for 30 nm active layer thickness along with HfO2 dielectric material. The optimized threshold voltage, subthreshold slope, mobility, and ION/IOFF ratio are 0.66 V, 0.067 V/decade, 6.44 cm2/V. s, and 109 respectively are obtained after simulating the Mg0.2Zn0.8O Thin Film Transistor on TCAD tool. Due to high ION/IOFF ratio low threshold voltage and good mobility this type of thin film transistor finds its viability in display devices, photodetectors, etc.

Keywords: Thin film transistor, Mg, ZnO, Active layer

This article belongs to Special Issue Conference ICASEMCT-2023: International Conference on Advancements in Smart Electronics, Materials and Communication Technologies

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Conference Open Access Original Research
Volume 11
Special Issue 05
Received May 24, 2023
Accepted July 25, 2023
Published August 11, 2023