Ultra-Low Voltage Metal Oxide Thin Film Transistor by Low-Temperature Annealed Solution Processed LiAlO2 Gate Dielectric

• Published in: Electronic materials letters Vol. 16; no. 1; pp. 22 - 34
• Main Authors: Sharma, Anand, Chourasia, Nitesh K., Acharya, Vishwas, Pal, Nila, Biring, Sajal, Liu, Shun-Wei, Pal, Bhola N.
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 2020; Springer Nature B.V; 대한금속·재료학회
• Subjects: Annealing; Carrier transport; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed Matter Physics; Density; Electron mobility; Low temperature; Low voltage; Magnetics and Photonics; Materials Science; Nanotechnology; Nanotechnology and Microengineering; Optical and Electronic Materials; Original Article - Electronics; Semiconductor devices; Silicon; Sol-gel processes; Surface roughness; Thin film transistors; Thin films; Transistors; 전자/정보통신공학; Metal oxide; Interface trap density; Low operating voltage; Thin film transistor; Dielectric; Sol-gel
• ISSN: 1738-8090; 2093-6788
• DOI: 10.1007/s13391-019-00184-1

Low surface-roughness and high-capacitance ion-conducting LiAlO 2 gate dielectric thin film has been fabricated by sol–gel technique to develop ultra-low voltage (≤ 1.0 V) indium-zinc-oxide thin film transistor (TFT). This LiAlO 2 dielectric shows α-LiAlO 2 and γ-LiAlO 2 phases those have been fabricated at two different temperatures. For both phases, mobile Li-ion is responsible to achieve a high dielectric constant (κ) of the material that helps to reduce the operating voltage of TFT. Additionally, lower surface roughness of LiAlO 2 thin film creates a low-density trap state in the semiconductor/dielectric interface which is capable to reduce operating voltage within 1.0-volt. The device with 700 °C annealed γ-LiAlO 2 gate dielectric shows the best device performance with an electron mobility of 25 cm 2 V −1  s −1 and an on/off ratio of 3 × 10 5 . Instead, 350 °C annealed α-LiAlO 2 dielectric require only one volt to saturate the drain current and shows its mobility and on/off ratio are 13.5 cm 2  V −1  s −1 and 1 × 10 4 respectively. Such kind of unusually low operation voltage TFT fabrication becomes possible because of the higher Li + mobility of α-LiAlO 2 gate dielectric and very low surface trap density. A model on carrier transport mechanism has been prepossessed to explain this achievement. Graphic abstract