(A) study on the characteristics of indium-aluminum-zinc oxide thin-film transistors according to aluminum content using plasma-enhanced atomic layer deposition

Abstract

This study aims to fabricate indium-aluminum-zinc oxide that compensates for the disadvantages of an indium-gallium-zinc oxide semiconductor, which is mainly used as a semiconductor for thin film transistors. Typical problems of indium-gallium zinc oxide include its narrow bandgap and instability under a constant gate voltage and thermal conditions. Aluminum oxide is superior to gallium in terms of adjusting the bandgap of an oxide semiconductor, and can suppress the formation of bandgap defects caused by oxygen vacancies owing to its strong binding energy with oxygen. Considering the cost, it is more advantageous to use aluminum compared to gallium, which is a rare earth metal. In this study, three methods for doping aluminum on indium-zinc oxide using plasma-enhanced atomic layer deposition were presented. The cause of difference in the performance of the thin film transistors according to each method was explained by the chemical composition of the oxide semiconductor and the passivation effect by hydrogen. Indium-aluminum-zinc oxide semiconductor thin film transistors with different aluminum contents were fabricated by adopting the deposition method with the best performance among the three recipes, and the electrical performance was analyzed. The difference in the transistor performance was explained based on the tendency of the oxygen vacancies according to the aluminum content. As a result, an indium-aluminum-zinc oxide semiconductor thin film transistor with a high mobility and stability was fabricated.